Parse vacuum to prevent wraparound correctly

When given an instance of vacuum to prevent wraparound, we fail to parse the log line (so it wouldn't have any parsed fields, which potentially prevents it from showing up in searches).

This adds support for the following example:

automatic aggressive vacuum to prevent wraparound of table "gitlabhq_production.pg_toast.pg_toast_559976213": index scans: 0
pages: 0 removed, 0 remain, 0 skipped due to pins, 0 skipped frozen
tuples: 0 removed, 0 remain, 0 are dead but not yet removable, oldest xmin: 1075895098
buffer usage: 25 hits, 1 misses, 1 dirtied
avg read rate: 5.923 MB/s, avg write rate: 5.923 MB/s
system usage: CPU: user: 0.00 s, system: 0.00 s, elapsed: 0.00 s

We continue to support the other modes of vacuum:

automatic aggressive vacuum of table "gitlabhq_production.public.draft_notes": index scans: 1
pages: 0 removed, 28066 remain, 0 skipped due to pins, 25122 skipped frozen
tuples: 812 removed, 198065 remain, 12 are dead but not yet removable, oldest xmin: 1075421965
buffer usage: 4484 hits, 42141 misses, 1368 dirtied
avg read rate: 135.962 MB/s, avg write rate: 4.414 MB/s
system usage: CPU: user: 0.25 s, system: 0.19 s, elapsed: 2.42 s

automatic vacuum of table "gitlabhq_production.pg_toast.pg_toast_2619": index scans: 1
pages: 0 removed, 13109 remain, 0 skipped due to pins, 8554 skipped frozen
tuples: 21 removed, 45467 remain, 275 are dead but not yet removable, oldest xmin: 1077011482
buffer usage: 4238 hits, 7 misses, 3 dirtied
avg read rate: 3.455 MB/s, avg write rate: 1.481 MB/s
system usage: CPU: user: 0.00 s, system: 0.00 s, elapsed: 0.01 s

Handy tool to check regex in ruby: https://rubular.com/

Closes gitlab-org/database-team/team-tasks#189 (closed)