Allow to delete group milestones

Closes #36138

See merge request gitlab-org/gitlab-ce!21057

Resolve "Size of checkout branch modal box is too small"

Closes #43625

See merge request gitlab-org/gitlab-ce!21381

Add Galician as an available language

Closes #43227

See merge request gitlab-org/gitlab-ce!21202

Resolve "[QA] `Test::Instance` doesn't use the correct path to spec files"

Closes #50746

See merge request gitlab-org/gitlab-ce!21394

Signed-off-by: Rémy Coutable <remy@rymai.me>

Compress all PNG images under doc/

See merge request gitlab-org/gitlab-ce!21329

The pngquant tool was used https://pngquant.org, and particularly, the
following command:

        /usr/bin/pngquant -f --skip-if-larger --ext .png --speed 1 image.png

Before: 47584K
After : 34924K

Merge branch '50526-flash-hideflash-sets-transition-style-test-fails-on-master-in-local-environment' into 'master'

Resolve ""Flash hideFlash sets transition style" test fails on master in local environment"

Closes #50526

See merge request gitlab-org/gitlab-ce!21376

Don't use ruby interpolation in externalized strings

Closes #50333

See merge request gitlab-org/gitlab-ce!21247

Add group name badge under group milestone

Closes #49292

See merge request gitlab-org/gitlab-ce!21384

Fix fallback logic for automatic MR title assignment

See merge request gitlab-org/gitlab-ce!20930

Rails5 update Gemfile.rails5.lock

See merge request gitlab-org/gitlab-ce!21388

Bitbucket Server importer: Eliminate most idle-in-transaction issues

See merge request gitlab-org/gitlab-ce!21173

Use slugs for default project path and sanitize names before import

See merge request gitlab-org/gitlab-ce!21367

Just like with the GitHub importer, the Bitbucket Server importer can hit the
default 60 s idle-in-transaction timeouts if it takes too long to create the
merge request. We solve this by using the same approach as the GitHub importer:

1. Bypass all validation and hooks in creating a merge request
2. Insert the Git data in a separate transaction

Part of #50021

Show `< 1%` when percent value evaluated is less than 1 on Stacked Progress Bar

Closes gitlab-ee#6028

See merge request gitlab-org/gitlab-ce!21306

[QA] Re-add Test::Instance for back-compatibility with GitLab < 11.3

See merge request gitlab-org/gitlab-ce!21339

Add Test plan issue template

See merge request gitlab-org/gitlab-ce!21227

Resolve "Follow up to "Styling of the MR widget's info and pipeline sections""

Closes #49110

See merge request gitlab-org/gitlab-ce!21206

When using ruby interpolation in externalized strings, they can't be
detected. Which means they will never be presented to be translated.

To mix variables into translations we need to use `sprintf`
instead.

Instead of:

    _("Hello #{subject}")

Use:

    _("Hello %{subject}) % { subject: 'world' }

API: Protected tags

Closes #39144

See merge request gitlab-org/gitlab-ce!14986

Feature flag to disable Hashed Storage migration when renaming a repository

Closes #50345

See merge request gitlab-org/gitlab-ce!21291

Drop WIP from changelog command in Danger comment

See merge request gitlab-org/gitlab-ce!21374

Refactor project_permissions_panel_data so it can be extended in EE easily

See merge request gitlab-org/gitlab-ce!21370

Refactor GitHub Importer database helpers into helper methods

See merge request gitlab-org/gitlab-ce!21357

Users importing from Bitbucket Cloud, Bitbucket Server, or GitHub
often complained about getting failed imports due to 422 errors.
This change ensures that project names are imported with names that
are guaranteed to pass the regular expression validation.

Part of #50021

Removing not necessarily indentations in update Ruby code block

See merge request gitlab-org/gitlab-ce!21364

[docs] Update CONTRIBUTING.md

See merge request gitlab-org/gitlab-ce!21355