As GitLab is planning on moving `ci_*` tables to a separate database we
need to start expanding our observability/logging/metrics to allow us to
distinguish between the different databases being queried.

We had already implemented logging per database by including the
database name (ie. what Postgres calls the database) in the log
statements in
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/63490 but later we
learnt this wasn't a good idea because we may want to use 2 different
Postgres servers with the same Database name (in fact that's what our
current migration plan involves). As such we need to use the name that
the GitLab application uses to distinguish between the 2 different
databases. This is the name used to configure the `config/database.yml`
and must be unique.

In the default case it does not have a name and Rails will call it
`primary`. This has the unfortunate result that this MR will add JSON
log keys `db_replica_primary_duration_s` and
`db_primary_primary_duration_s` because we already use the words
`primary/replica` to distinguish between our read-write primary and
read-only replicas. We plan to eventually force the
`config/database.yml` to name these `main` and `ci` and at that time
these log statements will be a little clearer. In the meantime this is
behind a feature flag so should not bother people that aren't intending
to try and make sense of these metrics.

Clarify RPC concurrency limit details

See merge request gitlab-org/gitlab!65388

Default on GraphQL boards feature flag [RUN ALL RSPEC] [RUN AS-IF-FOSS]

See merge request gitlab-org/gitlab!63118

Re-schedule `latest_pipeline_id` population with logger

See merge request gitlab-org/gitlab!66050

Add authentication note to releases API

See merge request gitlab-org/gitlab!66499

Refine moderate users content

See merge request gitlab-org/gitlab!66417

Fix audit events empty space

See merge request gitlab-org/gitlab!52590

Restrict omnibus self-managed registry test to pipeline main

See merge request gitlab-org/gitlab!66350

Update background migration to use main instead of master [RUN AS-IF-FOSS]

See merge request gitlab-org/gitlab!66492

https://gitlab.com/gitlab-org/gitaly/-/merge_requests/3537 updated the
default branch to be `master` instead of `main`. This broke
`backfill_snippet_repositories_spec.rb` because it expected to create
commits in `master`, but the default branch was `main`.

Since `main` is now the default, we should target the initial commit for
that branch.

Closes https://gitlab.com/gitlab-org/gitlab/-/issues/336538

Fix CRON setting when using gitaly-backup

See merge request gitlab-org/gitlab!65695

Create Form for Issue and Epic in Boards

See merge request gitlab-org/gitlab!65048

Allow updating merged results pipelines and merge trains via API [RUN AS-IF-FOSS]

See merge request gitlab-org/gitlab!56237

Move API CI related classes under Ci namespace

See merge request gitlab-org/gitlab!66263

Add SAML provider search to UsersFinder

See merge request gitlab-org/gitlab!66162

Remove helm doc warnings

See merge request gitlab-org/gitlab!66484

Add details about project feature settings

See merge request gitlab-org/gitlab!54276

Update GitLab Runner Helm Chart to 0.31.0/14.1.0

See merge request gitlab-org/gitlab!66447

Fix line numbers not being calculated properly

See merge request gitlab-org/gitlab!66475

Add project-level VSA for deploy metrics

See merge request gitlab-org/gitlab!65378

Resolve "Evaluate master/main usage and resolve issues - Package"

See merge request gitlab-org/gitlab!66469

Document wiki default branch behavior

See merge request gitlab-org/gitlab!66404

Remove marketing email opt-in for self-managed

See merge request gitlab-org/gitlab!66255

Clean up data-testid and use findByRole

See merge request gitlab-org/gitlab!66379

Add a note about sub group data

See merge request gitlab-org/gitlab!65365

nginx: modernise TLS config

See merge request gitlab-org/gitlab!65345

Cloud Licensing Updates to Docs

See merge request gitlab-org/gitlab!61314