These changes are ported over from
https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/1502 to reduce
the number of merge conflicts that may occur.

C: Style/MultilineOperationIndentation:
Align the operands of an expression in an assignment
spanning multiple lines.

Feedback:

* https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/9219#note_23343951
* https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/9219#note_23344036
* https://gitlab.com/gitlab-org/gitlab-ce/issues/27762#note_23344797

TODO: Add tests and screenshots

Feedback:
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/8664/diffs#note_22190504

The conflict happens when we try to update a build,
but fail to do so due to fact that we update the same build concurrently for two different runners.

Closes #26921

Fixes #26051.
Signed-off-by: NRémy Coutable <remy@rymai.me>

* We realized that headers were not set whenever we give 204
  because `render_api_error!` doesn't preserve the headers.

* We also realized that `update_runner_info` would be called in
  POST /builds/register every time therefore runner is updated
  every time, ticking the queue, making this last_update didn't
  work very well, and the test would be failing due to that.

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

Feedback:
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/8091#note_20253762

Feedback:
https://gitlab.com/gitlab-org/gitlab-ce/builds/7606797

Feedback:
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/8091#note_20222666

Closes #25309