Add external status checks total to ping

What does this MR do and why?

• Adds the total number of external service checks to the service ping.

Database Review

min

 Result  (cost=0.19..0.20 rows=1 width=8) (actual time=6.456..6.457 rows=1 loops=1)
   Buffers: shared read=2
   I/O Timings: read=6.352 write=0.000
   InitPlan 1 (returns $0)
     ->  Limit  (cost=0.14..0.19 rows=1 width=8) (actual time=6.422..6.423 rows=1 loops=1)
           Buffers: shared read=2
           I/O Timings: read=6.352 write=0.000
           ->  Index Only Scan using external_status_checks_pkey on public.external_status_checks  (cost=0.14..4.79 rows=94 width=8) (actual time=6.419..6.419 rows=1 loops=1)
                 Index Cond: (external_status_checks.id IS NOT NULL)
                 Heap Fetches: 0
                 Buffers: shared read=2
                 I/O Timings: read=6.352 write=0.000

Time: 7.111 ms  
  - planning: 0.587 ms  
  - execution: 6.524 ms  
    - I/O read: 6.352 ms  
    - I/O write: 0.000 ms  
  
Shared buffers:  
  - hits: 0 from the buffer pool  
  - reads: 2 (~16.00 KiB) from the OS file cache, including disk I/O  
  - dirtied: 0  
  - writes: 0  
 

max

Result  (cost=0.19..0.20 rows=1 width=8) (actual time=0.046..0.047 rows=1 loops=1)
   Buffers: shared hit=2
   I/O Timings: read=0.000 write=0.000
   InitPlan 1 (returns $0)
     ->  Limit  (cost=0.14..0.19 rows=1 width=8) (actual time=0.041..0.042 rows=1 loops=1)
           Buffers: shared hit=2
           I/O Timings: read=0.000 write=0.000
           ->  Index Only Scan using external_status_checks_pkey on public.external_status_checks  (cost=0.14..4.79 rows=94 width=8) (actual time=0.040..0.040 rows=1 loops=1)
                 Index Cond: (external_status_checks.id IS NOT NULL)
                 Heap Fetches: 0
                 Buffers: shared hit=2
                 I/O Timings: read=0.000 write=0.000

Time: 0.230 ms  
  - planning: 0.157 ms  
  - execution: 0.073 ms  
    - I/O read: 0.000 ms  
    - I/O write: 0.000 ms  
  
Shared buffers:  
  - hits: 2 (~16.00 KiB) from the buffer pool  
  - reads: 0 from the OS file cache, including disk I/O  
  - dirtied: 0  
  - writes: 0  
  

total

 Aggregate  (cost=5.26..5.27 rows=1 width=8) (actual time=0.070..0.071 rows=1 loops=1)
   Buffers: shared hit=5
   I/O Timings: read=0.000 write=0.000
   ->  Index Only Scan using external_status_checks_pkey on public.external_status_checks  (cost=0.14..5.02 rows=94 width=8) (actual time=0.033..0.049 rows=94 loops=1)
         Index Cond: ((external_status_checks.id >= 1) AND (external_status_checks.id < 100000))
         Heap Fetches: 0
         Buffers: shared hit=5
         I/O Timings: read=0.000 write=0.000

Time: 0.366 ms
  - planning: 0.230 ms
  - execution: 0.136 ms
    - I/O read: 0.000 ms
    - I/O write: 0.000 ms

Shared buffers:
  - hits: 5 (~40.00 KiB) from the buffer pool
  - reads: 0 from the OS file cache, including disk I/O
  - dirtied: 0
  - writes: 0

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.