Part of single codebase changes.

delete feature flag when disabling Rugged

See merge request gitlab-org/gitlab-ce!28289

EE Backport to CE of EE!12404

See merge request gitlab-org/gitlab-ce!28292

Extracted EE specific lines from favicon_spec.rb

See merge request gitlab-org/gitlab-ee!12404

Fix project visibility level validation

Closes #59379

See merge request gitlab-org/gitlab-ce!28305

Rename methods that conflict in Rails 5.2

Closes #55583

See merge request gitlab-org/gitlab-ce!28281

Use real mermaid for mermaid result

See merge request gitlab-org/gitlab-ce!28300

First iteration of documentation for writing end-to-end tests

See merge request gitlab-org/gitlab-ce!27603

framework that intends to make easier for every engineer to
contribute with the end-to-end tests creation, edition, and
improvements.

Improve installation from source

Closes #47483, #61549, and #50937

See merge request gitlab-org/gitlab-ce!28201

* Add a solution for JavaScript heap out of memory error when compiling
assets
* Add note about postgres database config
* Start gitaly before gitlab:setup as it won't work otherwise
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Merge branch '9228-geo-how-to-reconcile-differences-with-geo-checksum-mismatches-docs' into 'master'

Document how to reconcile differences with Geo checksum mismatches

Closes gitlab-ee#9228

See merge request gitlab-org/gitlab-ce!28183

Add a "Force authentication for approval" option for merge request approvals.

See merge request gitlab-org/gitlab-ee!10364

Update ruby_parser for ruby 2.6

See merge request gitlab-org/gitlab-ce!28295

Update ruby_parser for ruby 2.6

See merge request gitlab-org/gitlab-ee!12651

Resolve "Remove ignore_column ci_id"

Closes #61302

See merge request gitlab-org/gitlab-ce!28234

Ensure that dependencies are installed before running frontend tests

See merge request gitlab-org/gitlab-ce!28236

CE backport: Remove non-semantic use of `.row` in member listing controls

See merge request gitlab-org/gitlab-ce!28204

Resolve "Remove non-semantic use of `.row` in member listing controls"

Closes #11542

See merge request gitlab-org/gitlab-ee!12466

Adds changelog entry for Matomo string website ID support

See merge request gitlab-org/gitlab-ce!28244