Previously, the API to retrieve discussions from merge requests often
generated hundreds of Gitaly calls to determine whether a system note
should be shown to the user. It did this by:

1. Rendering the Markdown
2. Extracting cross-references from the Markdown
3. For cross-references that were commits, a Gitaly FindCommit RPC
   would be issued to validate that the commit exists.

The last step is unnecessary because we don't need to display a commit
if the user doesn't have access to the project in the first place.

`RendersNotes#prepare_notes_for_rendering` is already used in
`MergeRequestsController`, which is why we don't see N+1 Gitaly calls
there. We use it here to optimize the note redaction process.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/65957

Documentation: fix push options capabilities

See merge request gitlab-org/gitlab-ce!31792

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/31068 forgot to
add a short description of the new push options that it added.

Embed metrics charts in issues - docs

See merge request gitlab-org/gitlab-ce!30849

Docs: remove extra quote from doc/install/installation.md

See merge request gitlab-org/gitlab-ce!31785

CE Migration Backport: Add flag to object storage

See merge request gitlab-org/gitlab-ce!31695

Fix project avatar image in Slack pipeline notifications

Closes #66008

See merge request gitlab-org/gitlab-ce!31788

Add usage pings for source code pushes

See merge request gitlab-org/gitlab-ce!31734

Source Code Usage Ping for Create SMAU

Bump Helm to 2.14.3 and kubectl to 1.11.10

See merge request gitlab-org/gitlab-ce!31716

Expand variables only when needed

See merge request gitlab-org/gitlab-ce!31772

Rework push mirror retries

See merge request gitlab-org/gitlab-ce!31247

**Prevention of running 2 simultaneous updates**

Instead of using `RemoteMirror#update_status` and raise an error if
it's already running to prevent the same mirror being updated at the
same time we now use `Gitlab::ExclusiveLease` for that.

When we fail to obtain a lease in 3 tries, 30 seconds apart, we bail
and reschedule. We'll reschedule faster for the protected branches.

If the mirror already ran since it was scheduled, the job will be
skipped.

**Error handling: Remote side**

When an update fails because of a `Gitlab::Git::CommandError`, we
won't track this error in sentry, this could be on the remote side:
for example when branches have diverged.

In this case, we'll try 3 times scheduled 1 or 5 minutes apart.

In between, the mirror is marked as "to_retry", the error would be
visible to the user when they visit the settings page.

After 3 tries we'll mark the mirror as failed and notify the user.

We won't track this error in sentry, as it's not likely we can help
it.

The next event that would trigger a new refresh.

**Error handling: our side**

If an unexpected error occurs, we mark the mirror as failed, but we'd
still retry the job based on the regular sidekiq retries with
backoff. Same as we used to

The error would be reported in sentry, since its likely we need to do
something about it.

Only expire tag cache once per push

See merge request gitlab-org/gitlab-ce!31641

This makes us to expand variables only when needed,
instead of requesting all variables each time.

This specifically helps in situation when explicit name
of `environment: production` is used.

Included missing fields, removed non existinting ones, improved examples

This commit fixes the project avatar images that are rendered in the
footer of Slack pipeline notifications.  Previously, the image URLs
provided to Slack were relative URLs; now they are absolute.

Return `429` instead of `302` on Rate Limiter on the raw endpoint

See merge request gitlab-org/gitlab-ce!31777

It was originally returning 302 when the rate limit kicks in, because
using the the correct status code makes it easier to track rate limiting
events

Related to https://gitlab.com/gitlab-org/gitlab-ce/issues/65974

Backport of https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/14599

See merge request gitlab-org/gitlab-ce!31573

representing error message with .flash-container element

See merge request gitlab-org/gitlab-ce!31636

Merge branch '34414-update-personal-access-token-scope-descriptions-to-reflect-registry-permissions' into 'master'

Update personal access token api scope description

Closes #34414

See merge request gitlab-org/gitlab-ce!31759

Update links.md to give more consistency with the rest of the documentation

See merge request gitlab-org/gitlab-ce!31693

Add BrowserStack details to Frontend Dev Guide

See merge request gitlab-org/gitlab-ce!31744

Part of Docker Regsitry Replication feature for Geo

Make cron notation parser a proper note

See merge request gitlab-org/gitlab-ce!31542

Previously each tag in a push would invoke the Gitaly `FindAllTags` RPC
since the tag cache would be invalidated with every tag.

We can eliminate those extraneous calls by expiring the tag cache once
in `PostReceive` and taking advantage of the cached tags.

Relates to https://gitlab.com/gitlab-org/gitlab-ce/issues/65795

Only expire branch cache once per push

See merge request gitlab-org/gitlab-ce!31653

Change the language in the Licensing section

See merge request gitlab-org/gitlab-ce!29750

Docs for self monitoring MVC

See merge request gitlab-org/gitlab-ce!31530

- The self-monitoring project can be connected to any Prometheus
instance. Make this more clear in the docs.

Update permissions for dependency list

See merge request gitlab-org/gitlab-ce!31666

Move different licensing content from README to LICENSE file