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.

[EE] Rework push mirror retries

See merge request gitlab-org/gitlab-ee!14974

**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

Rename comparer file for generic use

See merge request gitlab-org/gitlab-ee!15133

Geo - Remove feature flag for Docker container registries replication

Closes #2870

See merge request gitlab-org/gitlab-ee!15135

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.

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

Geo fully support replication for Docker container registries, and
the feature flag can be removed.

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

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

[Geo] Configure capacity for Docker sync service(3/4)

See merge request gitlab-org/gitlab-ee!14599

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

EE 10161 hide issuable urls on vulnerability feedback

Closes #10161

See merge request gitlab-org/gitlab-ee!14928

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