Use CI_COMMIT_REF_SLUG when building assets image

See merge request gitlab-org/gitlab-ce!22756

* Using CI_COMMIT_REF_NAME fails when the branch or tag contains special
characters

CE backport from  Added a search bar to `Admin > Geo > Projects`

See merge request gitlab-org/gitlab-ce!22747

Use merge_db_schema for db/schema.rb conflicts

See merge request gitlab-org/gitlab-ce!22692

This allows EE code to reuse the search partial and append additional
query parameters to it, and have it preserved when searching.

Add dynamic timer for delayed jobs in job list

See merge request gitlab-org/gitlab-ce!22656

This Gem can be used to automatically resolve merge conflicts in
db/schema.rb. To use it you still need to initialise the configuration,
which can be done by running:

    merge_db_schema-init --force

See https://gitlab.com/gitlab-org/release/framework/issues/42 for more
information.

add referenced merge_requests endpoint

Closes #39157

See merge request gitlab-org/gitlab-ce!21806

Fixes automatic URL formatting on Maven Page

See merge request gitlab-org/gitlab-ce!22727

Improve markdown and fix links that don't render correctly

See merge request gitlab-org/gitlab-ce!22735

Improve markdown and fix links that don't render correctly

See merge request gitlab-org/gitlab-ce!22737

Improve markdown and fix links that don't render correctly

See merge request gitlab-org/gitlab-ce!22738

Resolve "Filter by `None`/`Any` for milestone in issues/mrs API"

Closes #52382

See merge request gitlab-org/gitlab-ce!22637

Refactor SSH keys docs for Windows clients

Closes #46398 and #46399

See merge request gitlab-org/gitlab-ce!21004

Fix typos in comments and specs

See merge request gitlab-org/gitlab-ce!22683

Reduce SQL queries needed to load open merge requests

See merge request gitlab-org/gitlab-ce!22709

Drop gcp_clusters table

See merge request gitlab-org/gitlab-ce!22713

Whitelist none method from ActiveRecord::Querying

See merge request gitlab-org/gitlab-ce!22726

Prettify remaining files with differences in CE and EE

See merge request gitlab-org/gitlab-ce!22702