Add Geo rake task descriptions

Closes #3366

See merge request gitlab-org/gitlab-ee!2925

Revise GitLab Geo documentation

Closes #3365 and #3400

See merge request gitlab-org/gitlab-ee!2858

Removed issues link from the breadcrumbs in issue boards

Closes gitlab-ce#37875

See merge request gitlab-org/gitlab-ee!2920

Only set status variables if Geo node is a secondary

See merge request gitlab-org/gitlab-ee!2903

Fix EE specific nav items not having active state

See merge request gitlab-org/gitlab-ee!2918

To increase visibility of Geo rake tasks, add description so `rake -T`
shows them.

Closes gitlab-org/gitlab-ee#3366

Updated Doc: Omitting AWS access key and ID key=>value pairs when using AWS IAM profiles

See merge request gitlab-org/gitlab-ee!2892

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/37875

Fixes include:
- GitLab 10.0 depends on the tracking database (because of the removal
  of System Hooks in gitlab-org/gitlab-ee!2644), therefore the docs
  should clearly state how to set up and update the Geo tracking
  database.

- To initiate synchronization it's no longer needed to push first.
  Geo will automatically pick up new projects, and it's no longer needed
  to push to the repo before GitLab Geo will start syncing.

- Small changes to improve consistency through the whole docs.

Closes gitlab-org/gitlab-ee#3365 and gitlab-org/gitlab-ee#3400

Use proper args for gpg command used in docs

See merge request gitlab-org/gitlab-ee!2910

Adjust inconsistent failures on Billings controller tests

See merge request gitlab-org/gitlab-ee!2909

Ensure #route_setting is available before calling it

See merge request !2908

Fix ordering of Gemfiles

See merge request !2907

In the context of an exception, #route_setting is not available.

See:

- https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/14178#note_40259442
- https://github.com/ruby-grape/grape/blob/df79bc35e43f0d5b6cbd666b587cf4640de174b8/lib/grape/middleware/error.rb#L59Signed-off-by: Rémy Coutable <remy@rymai.me>

Fixed boards text in the project sidebar

Closes #3415

See merge request !2890

fixing a typo in code example for marking all todo's as done

See merge request !2901

Fix when pushing without a branch name

Closes #3393

See merge request !2879

Closes #3415

Geo - Ignore S3-backed LFS objects on secondary nodes

Closes #3371

See merge request !2889

Improve Geo repository sync performance for larger databases

Closes #3269

See merge request !2887

Document work around when upgrading to 9.3/9.4 for MySql instances.

Closes gitlab-ce#36422

See merge request !2897

Stop needing SSH keys for Geo primaries

Closes #3340

See merge request !2861

Pick a released security fix into master

See merge request !2895

Decrease Perceived and Cyclomatic Complexity

See merge request !2874

Make sure we validate the branch name being pushed even if no commits
are in the push.

Otherwise it would be possible to create branches that aren't supposed
to be allowed.