Add global search tests

Closes #188 (closed)

Adds in API and Web tests for Global Search endpoints.

Tests cover data that we don't really have at the moment such as Issues, etc... but we can still add them in a test now for new data hopefully coming in soon.

Results:

* Environment:                25k
* Environment Version:        12.7.0-pre `214c605dd1b`
* Option:                     60s_500rps
* Date:                       2020-02-12
* Run Time:                   2m 11.74s (Start: 14:13:11 UTC, End: 14:15:23 UTC)
* GPT Version:                v1.1.2

█ Overall Results Score: 96.2%

NAME                 | RPS   | RPS RESULT           | TTFB AVG  | TTFB P90             | REQ STATUS     | RESULT
---------------------|-------|----------------------|-----------|----------------------|----------------|-----------------
api_v4_search_global | 500/s | 255.73/s (>120.00/s) | 3119.70ms | 8973.45ms (<15000ms) | 98.93% (>95%)  | Passed
web_search_global    | 50/s  | 48.1/s (>40.00/s)    | 209.53ms  | 388.11ms (<500ms)    | 100.00% (>95%) | FAILED²

    █ API - Global Search

    data_received...................: 127 MB 2.1 MB/s
    data_sent.......................: 2.8 MB 48 kB/s
    group_duration..................: avg=9172.02ms min=1837.73ms med=9306.17ms max=11979.51ms p(90)=9971.62ms p(95)=10213.12ms
    http_req_blocked................: avg=95.11ms   min=0.00ms    med=120.31ms  max=2667.11ms  p(90)=161.65ms  p(95)=252.05ms
    http_req_connecting.............: avg=92.37ms   min=0.00ms    med=120.19ms  max=321.47ms   p(90)=160.90ms  p(95)=247.99ms
    http_req_duration...............: avg=3142.37ms min=119.60ms  med=2053.02ms max=11789.77ms p(90)=9098.60ms p(95)=9474.21ms
    http_req_receiving..............: avg=22.62ms   min=0.02ms    med=0.05ms    max=251.79ms   p(90)=123.26ms  p(95)=125.93ms
    http_req_sending................: avg=0.05ms    min=0.01ms    med=0.04ms    max=31.27ms    p(90)=0.07ms    p(95)=0.08ms
    http_req_tls_handshaking........: avg=0.00ms    min=0.00ms    med=0.00ms    max=0.00ms     p(90)=0.00ms    p(95)=0.00ms
    http_req_waiting................: avg=3119.70ms min=119.54ms  med=2052.97ms max=11668.49ms p(90)=8973.45ms p(95)=9347.17ms
    ✓ { endpoint:issues }...........: avg=1751.09ms min=119.94ms  med=1824.38ms max=4530.22ms  p(90)=2321.98ms p(95)=2465.77ms
    ✓ { endpoint:merge_requests }...: avg=8882.10ms min=119.54ms  med=9057.68ms max=11668.49ms p(90)=9722.86ms p(95)=9929.96ms
    ✓ { endpoint:milestones }.......: avg=1941.16ms min=119.67ms  med=2027.68ms max=4348.97ms  p(90)=2502.38ms p(95)=2637.56ms
    ✓ { endpoint:projects }.........: avg=2022.57ms min=119.88ms  med=2087.61ms max=4615.84ms  p(90)=2587.37ms p(95)=2738.25ms
    ✓ { endpoint:users }............: avg=1736.24ms min=121.00ms  med=1818.27ms max=4265.85ms  p(90)=2303.59ms p(95)=2447.62ms
  ✓ http_reqs.......................: 15344  255.73289/s
    ✓ { endpoint:issues }...........: 3159   52.649909/s
    ✓ { endpoint:merge_requests }...: 2748   45.799921/s
    ✓ { endpoint:milestones }.......: 3142   52.366576/s
    ✓ { endpoint:projects }.........: 3144   52.399909/s
    ✓ { endpoint:users }............: 3151   52.516576/s
    iteration_duration..............: avg=9168.71ms min=0.79ms    med=9305.85ms max=11979.56ms p(90)=9971.47ms p(95)=10212.95ms
    iterations......................: 2748   45.799921/s
  ✓ successful_requests.............: 98.93% ✓ 13593 ✗ 147
    vus.............................: 1      min=1   max=500
    vus_max.........................: 500    min=500 max=500

    █ Web - User Page

    data_received.........................: 32 MB   528 kB/s
    data_sent.............................: 315 kB  5.2 kB/s
    group_duration........................: avg=8805.80ms min=742.29ms med=9787.39ms max=35597.28ms p(90)=10018.97ms p(95)=10055.69ms
    http_req_blocked......................: avg=90.07ms   min=0.00ms   med=100.96ms  max=159.06ms   p(90)=120.35ms   p(95)=121.10ms
    http_req_connecting...................: avg=34.98ms   min=0.00ms   med=0.00ms    max=159.01ms   p(90)=120.24ms   p(95)=120.94ms
    http_req_duration.....................: avg=269.39ms  min=137.70ms med=274.86ms  max=30314.06ms p(90)=507.66ms   p(95)=568.49ms
    http_req_receiving....................: avg=59.82ms   min=0.03ms   med=0.25ms    max=150.88ms   p(90)=120.53ms   p(95)=121.28ms
    http_req_sending......................: avg=0.04ms    min=0.01ms   med=0.03ms    max=0.37ms     p(90)=0.06ms     p(95)=0.07ms
    http_req_tls_handshaking..............: avg=0.00ms    min=0.00ms   med=0.00ms    max=0.00ms     p(90)=0.00ms     p(95)=0.00ms
    http_req_waiting......................: avg=209.53ms  min=137.65ms med=172.48ms  max=30313.93ms p(90)=388.11ms   p(95)=447.72ms
    ✓ { endpoint:issues_count }...........: avg=154.47ms  min=144.53ms med=150.20ms  max=276.49ms   p(90)=168.98ms   p(95)=171.73ms
    ✓ { endpoint:issues }.................: avg=191.92ms  min=173.58ms med=183.87ms  max=579.45ms   p(90)=206.24ms   p(95)=219.02ms
    ✓ { endpoint:merge_requests_count }...: avg=159.27ms  min=149.05ms med=153.97ms  max=274.83ms   p(90)=173.93ms   p(95)=176.34ms
    ✗ { endpoint:merge_requests }.........: avg=463.61ms  min=382.79ms med=447.45ms  max=790.91ms   p(90)=537.50ms   p(95)=561.01ms
    ✓ { endpoint:milestones_count }.......: avg=254.75ms  min=140.72ms med=145.46ms  max=30313.93ms p(90)=164.13ms   p(95)=167.61ms
    ✓ { endpoint:milestones }.............: avg=207.97ms  min=188.65ms med=199.78ms  max=434.01ms   p(90)=225.62ms   p(95)=247.75ms
    ✓ { endpoint:projects_count }.........: avg=145.22ms  min=137.65ms med=142.11ms  max=214.60ms   p(90)=159.51ms   p(95)=162.55ms
    ✓ { endpoint:projects }...............: avg=192.54ms  min=177.57ms med=186.98ms  max=308.70ms   p(90)=209.81ms   p(95)=219.91ms
    ✓ { endpoint:users_count }............: avg=145.13ms  min=137.72ms med=141.44ms  max=263.62ms   p(90)=159.11ms   p(95)=161.95ms
    ✓ { endpoint:users }..................: avg=183.23ms  min=167.70ms med=175.44ms  max=512.91ms   p(90)=198.35ms   p(95)=210.54ms
  ✓ http_reqs.............................: 2886    48.099835/s
    ✓ { endpoint:issues_count }...........: 289     4.81665/s
    ✓ { endpoint:issues }.................: 289     4.81665/s
    ✓ { endpoint:merge_requests_count }...: 289     4.81665/s
    ✓ { endpoint:merge_requests }.........: 286     4.76665/s
    ✓ { endpoint:milestones_count }.......: 289     4.81665/s
    ✓ { endpoint:milestones }.............: 288     4.799984/s
    ✓ { endpoint:projects_count }.........: 290     4.833317/s
    ✓ { endpoint:projects }...............: 289     4.81665/s
    ✓ { endpoint:users_count }............: 289     4.81665/s
    ✓ { endpoint:users }..................: 288     4.799984/s
    iteration_duration....................: avg=8775.14ms min=0.19ms   med=9786.34ms max=35597.32ms p(90)=10018.93ms p(95)=10055.21ms
    iterations............................: 286     4.76665/s
  ✓ successful_requests...................: 100.00% ✓ 2860 ✗ 0
    vus...................................: 1       min=1  max=50
    vus_max...............................: 50      min=50 max=50