Add gauges for threads using db connections

See merge request gitlab-org/gitlab!36632

This adds a gauge exposing the configured number of threads we expect
to be running and using the database called
`gitlab_ruby_threads_concurrency_total`.

It also adds `gitlab_ruby_threads_total`.

This gauge has a `thread_name` label used to identify the kind of
thread. For unnamed threads the label will contain `unnamed`.

To identify sidekiq worker threads, that before had no name, we set it
in the `Gitlab::SidekiqMiddleware::Metrics` server middleware. So we
can distinguish it from other running threads.

The `uses_db_connection` label indicates if the thread has at some
point connected to the database. We use the same subscriber as we do
for the query counts to flip this value on the thread.

Fixed Ops-Settings page titles capitalization

See merge request gitlab-org/gitlab!37259

Corrected the title cased titles to be sentenced cased

Limit database deprecation notice window

Closes #227292

See merge request gitlab-org/gitlab!37009

We decided to make the .days_until_deprecation method private
as its functionality is tested in other tests. This commit also
removes the associated test for the newly private method.

Remove :skip_web_ui_code_owner_validations feature flag

See merge request gitlab-org/gitlab!37367

Fix local tiller default enabled inconsistency

See merge request gitlab-org/gitlab!37494

I missed this in https://gitlab.com/gitlab-org/gitlab/-/merge_requests/35562

See also https://gitlab.com/gitlab-org/gitlab/-/issues/209736

Fix N+1 for project/:id/issues API endpoint

See merge request gitlab-org/gitlab!37508

Fix dev PAT fixture creation

See merge request gitlab-org/gitlab!37517

Add missing version notes to resource events API pages

Closes #225670

See merge request gitlab-org/gitlab!37449

Docs: Add documentation about Babel polyfills

See merge request gitlab-org/gitlab!24527

Add docs about finding polyfills in webpack report

Resolve "Explain optional merge request approval rules in documentation"

Closes #216633

See merge request gitlab-org/gitlab!31151

Existing PAT has wrong digest
and therefore doesn't work.

This makes the creation more
robust and future proof.

Improve checks for path traversal validation

See merge request gitlab-org/gitlab!33114

Coerce repository_storages_weighted, removes repository_storages

See merge request gitlab-org/gitlab!36376

Preload milestones and closed_by users

Inverse pipeline for its build associations

See merge request gitlab-org/gitlab!37478

Remove old export file when requesting new project export using API

See merge request gitlab-org/gitlab!37427

Refactor the HLL unique counting between visits and actions

See merge request gitlab-org/gitlab!36583

Exclude license scanner types from SecurityScannerType enum

See merge request gitlab-org/gitlab!37318

Disable parallel matrix feature flag

See merge request gitlab-org/gitlab!37501

Added Security prefix for clarity

Closes gitlab-runner#25663

See merge request gitlab-org/gitlab!37380

Geo - Fix Node Form Breadcrumbs

Closes #230331

See merge request gitlab-org/gitlab!37366

This change adds the proper middle layer to the
breadcrumbs for the Geo Node Form.

Refactor job_app not to use js-selectors

Closes #223211

See merge request gitlab-org/gitlab!37343

This commit removes all js selectors that are
use in job_app and related tests. While I was
at it, I also refactored most of the test files
I was touching to use VTU.

Fix ambiguous query error on milestone_id

See merge request gitlab-org/gitlab!37451

Make the Edit Release and New Release pages use the same Vue component

See merge request gitlab-org/gitlab!37460

https://gitlab.com/gitlab-org/gitlab/-/merge_requests/33705 introduced a
production incident
(https://gitlab.com/gitlab-com/gl-infra/production/-/issues/2442). Disable
this feature flag by default until we validate this feature is stable.

Assign Alerts To Do docs

See merge request gitlab-org/gitlab!34447

Update GitLab UI/SVG

See merge request gitlab-org/gitlab!37456

Clarify rules on jargon and uncommon words

See merge request gitlab-org/gitlab!36627