`perform_enqueued_jobs` is a Sidekiq method.
Using this method violates the Dependency inversion principle[0].

This commit replaces `perform_enqueued_jobs` with ActiveJob's abstract
method `perform_enqueued_jobs` in specs.

[0]: https://en.wikipedia.org/wiki/Dependency_inversion_principle

Update merge_request.png in docs

See merge request gitlab-org/gitlab-ce!20730

Update docs milestones

See merge request gitlab-org/gitlab-ce!20731

Merge branch '6104-extract-ee-specific-files-lines-for-some-platform-related-project-views' into 'master'

[CE] Resolve "Extract EE specific files/lines for some platform related project views"

See merge request gitlab-org/gitlab-ce!19859

Bring JsonLogger to CE

See merge request gitlab-org/gitlab-ce!20755

Fix one disabled spec of comment posting.

See merge request gitlab-org/gitlab-ce!20747

This backports a module that was in EE for Geo so that other modules
can have structured logging support.

Resolve "Replace all usages of `label-light` with `label-bold`"

Closes #47530 and #41725

See merge request gitlab-org/gitlab-ce!20727

Resolve ""Jump to first/next unresolved discussion" jumps to resolved discussions"

Closes #48817 and #48602

See merge request gitlab-org/gitlab-ce!20434

Specify Jupyter Image to use with JupyterHub Installation

See merge request gitlab-org/gitlab-ce!20714

Change Discussion label to Plan label and add Create label

See merge request gitlab-org/gitlab-ce!20717

Resolve "Unable to save user profile update with Safari"

Closes #45443

See merge request gitlab-org/gitlab-ce!20676

Docs: Fix indent problem in mysql_to_postgresql.md

See merge request gitlab-org/gitlab-ce!20736

Fixing bug with wiki ref in ProjectSearchResults

Closes #49014

See merge request gitlab-org/gitlab-ce!20722

Enables Bootsnap to GitLab (development)

Closes #45230

See merge request gitlab-org/gitlab-ce!20743

Resolve "Ability to download single file"

Closes #23705

See merge request gitlab-org/gitlab-ce!20480

Fix deserializing YAML variables when a build has been imported

Closes #49406

See merge request gitlab-org/gitlab-ce!20713

This will enable bootsnap whenver the gem is available.

Remove refs cleanup job

See merge request gitlab-org/gitlab-ce!20716

First version of pry_debugging.md

Closes #45728

See merge request gitlab-org/gitlab-ce!20740

Gitaly migrate old DB migrations

Closes gitaly#1106

See merge request gitlab-org/gitlab-ce!20708

[ci skip]

Migrate add_remote, remove_remote, fetch_internal_remote to gitaly

See merge request gitlab-org/gitlab-ce!20724

Don't overflow project/group dropdown results

Closes #49382 and #49379

See merge request gitlab-org/gitlab-ce!20704