CI: increase PG max_connections to 200

What does this MR do?

CI: increase PG max_connections to 200

PG defaults to 100 connections.

Testing shows that QA can run in excess of 120. Bump to 200, and cross fingers. Sidekiq can use in excess of 40 connections per Pod.

Related issues

Related to #4875 (closed)

Test case

Without this change, the logs of PostgreSQL instance will show FATAL: remaining connection slots are reserved for non-replication superuser connections once QA has "fully" spun up load. (HPAs limit to 2x Sidekiq, 3x Webservice)

With this change, sufficient connections are available for all tests to pass. Load observed north of 120.

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion.

Required

• Merge Request Title and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com
• When ready for review, MR is labeled "~workflow::ready for review" per the Distribution MR workflow

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA
• Equivalent MR/issue for omnibus-gitlab opened
• Validate potential values for new configuration settings. Formats such as integer 10, duration 10s, URI scheme://user:passwd@host:port may require quotation or other special handling when rendered in a template and written to a configuration file.