Optimize API /groups/:id/projects by preloading assocations

Closes #40308

See merge request gitlab-org/gitlab-ce!15475

Resolve "Upgrade Rails to 4.2.10"

Closes #40691

See merge request gitlab-org/gitlab-ce!15662

Add notice to Gollum initializer

See merge request gitlab-org/gitlab-ce!15713

Update parser gem to remove warning about wrong ruby version

See merge request gitlab-org/gitlab-ce!15720

Remove db/fixtures/test/01_admin.rb (EE backport)

See merge request gitlab-org/gitlab-ce!15711

Port of EE translations

See merge request gitlab-org/gitlab-ce!15718

New Crowdin translations

See merge request gitlab-org/gitlab-ee!3378

Resolve "Email notifications not sent as expected"

Closes #38862

See merge request gitlab-org/gitlab-ce!15686

This backport a change made in the CE upstream MR, see
https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/3593Signed-off-by: Rémy Coutable <remy@rymai.me>

Fix typo in Elasticsearch

Closes #40770

See merge request gitlab-org/gitlab-ce!15699

For a user with the mention notification level set, the type of their
corresponding NotificationRecipient must be :mention for them to receive an
email.

We set this correctly on notes, but we weren't adding it on new issues or MRs -
perhaps because these users are also participants. But the type of the
NotificationRecipient in that case would be :participant, not mention, so we
have to add the mentioned users manually when creating an issue or MR.

When editing an issue or MR, and there are newly-mentioned users to email, we
still use the :new_issue and :new_merge_request actions, so this works for that
case as well.

Fix the fork project functionality for projects with hashed storage

Closes #40711

See merge request gitlab-org/gitlab-ce!15671

Add version that the mermaid support was introduced

See merge request gitlab-org/gitlab-ce!15688

Add underline hover state to all links

Closes #24129

See merge request gitlab-org/gitlab-ce!15638

Keep track of all storage keys in a set

See merge request gitlab-org/gitlab-ce!15613

Added default order to UserFinder

Closes #40407

See merge request gitlab-org/gitlab-ce!15679

Note the dependency on gitlab-shell v5.10.0

Don't disable the Rails mailer when seeding the test environment

See merge request gitlab-org/gitlab-ce!15690

Documentation bug fixes: Added procedure to disable built-in Issues.

See merge request gitlab-org/gitlab-ce!15581

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

Changes since 4.2.8:

- [No change in ActionMailer](https://github.com/rails/rails/blob/v4.2.10/actionmailer/CHANGELOG.md)
- [1 change and 1 regression fix in ActionPack](https://github.com/rails/rails/blob/v4.2.10/actionpack/CHANGELOG.md)
- [No change in ActiveModel](https://github.com/rails/rails/blob/v4.2.10/activemodel/CHANGELOG.md)
- [7 fixes in ActiveRecord](https://github.com/rails/rails/blob/v4.2.10/activerecord/CHANGELOG.md)
- [5 fixes in ActiveSupport](https://github.com/rails/rails/blob/v4.2.10/activesupport/CHANGELOG.md)
- [No change in Railties](https://github.com/rails/rails/blob/v4.2.10/railties/CHANGELOG.md)
Signed-off-by: Rémy Coutable <remy@rymai.me>

Comments from code review applied. Also switched forked_from_project and ForkedProjectLinks to ForkNetworkMember