Removes expensive dead code on main MR page request

Closes #51172

See merge request gitlab-org/gitlab-ce!22153

Remove duplicate button from the markdown header toolbar

See merge request gitlab-org/gitlab-ce!22192

Resolve "Pipeline graph is not vertically aligned in commit page"

Closes #52193

See merge request gitlab-org/gitlab-ce!22173

Fix comments in app/models/note.rb

See merge request gitlab-org/gitlab-ce!22171

Update installation and update docs for 11 4

See merge request gitlab-org/gitlab-ce!22030

Clean up ActiveRecord code in TodosFinder and TodoService

See merge request gitlab-org/gitlab-ce!21838

Add note in docs for docker executor for interactive web terminal

See merge request gitlab-org/gitlab-ce!21880

Fix links to auth resources external to docs

See merge request gitlab-org/gitlab-ce!22180

This refactors the TodoService class according to our code reuse
guidelines. The resulting code is a wee bit more verbose, but it allows
us to decouple the column names from the input, resulting in fewer
changes being necessary when we change the schema.

One particular noteworthy line in TodoService is the following:

    todos_ids = todos.update_state(state)

Technically this is a violation of the guidelines, because
`update_state` is a class method, which services are not supposed to use
(safe for a few allowed ones). I decided to keep this, since there is no
alternative. `update_state` doesn't produce a relation so it doesn't
belong in a Finder, and we can't move it to another Service either. As
such I opted to just use the method directly.

Cases like this may happen more frequently, at which point we should
update our documentation with some sort of recommendation. For now, I
want to refrain from doing so until we have a few more examples.

This refactors the TodosFinder finder according to the new code reuse
rules, as enforced by the CodeReuse cops. I also changed some of the
methods to use regular if statements, instead of assignments and/or
early returns. This results in a more natural flow when reading the
code, and it makes it harder to accidentally return the wrong result.

docs: cleanup term settings wording

See merge request gitlab-org/gitlab-ce!22162

Replace old "secret variables" image for variables with new "variables" image

See merge request gitlab-org/gitlab-ce!22184

Redirect to the pipeline builds page when a build is canceled

Closes #39161

See merge request gitlab-org/gitlab-ce!21595

Resolve "Merge request buttons spacing incorrect"

Closes #48494

See merge request gitlab-org/gitlab-ce!22135

Docs - Prefilled fields for new issue link

See merge request gitlab-org/gitlab-ce!22082

Added note to clarify values for hook-name.d

See merge request gitlab-org/gitlab-ce!22165

Improve QA page README

See merge request gitlab-org/gitlab-ce!22176

Update explanation about the `extends` feature

See merge request gitlab-org/gitlab-ce!22043

Add note about hostname *and* port needing to match for `DOCKER_AUTH_CONFIG`

See merge request gitlab-org/gitlab-ce!22064

Fix link to EE-only doc and fix lint issues

See merge request gitlab-org/gitlab-ce!22178

Fix link to MR-template and other improvements

See merge request gitlab-org/gitlab-ce!22179

Fix indentation in GPG documentation

See merge request gitlab-org/gitlab-ce!22132

Enable more frozen string in lib/**/*.rb

See merge request gitlab-org/gitlab-ce!22174

Rails 5: fix mysql milliseconds problems in scheduled build specs

See merge request gitlab-org/gitlab-ce!22170

Update templates for 11.4

See merge request gitlab-org/gitlab-ce!22188

Prune events older than 2 years instead of 12 months

See merge request gitlab-org/gitlab-ce!22145

Remove duplicate Sentry logging for GRPC exceptions

See merge request gitlab-org/gitlab-ce!22187

Update licenses for 11.4

See merge request gitlab-org/gitlab-ce!22189

Fix issues controller N+1 failure

See merge request gitlab-org/gitlab-ce!22141

Updates Laravel.gitlab-ci.yml template

See merge request gitlab-org/gitlab-ce!22167

Render log artifact files in GitLab

See merge request gitlab-org/gitlab-ce!22112