Instead of using:
`coverage: /\(\d+.\d+%\) covered/`

This structure must be used now:
```
coverage:
  output_filter: /\(\d+.\d+%\) covered/`
```

The surrounding '/' is optional.

This commit:
* Turns `coverage_regex` into `coverage` entry in yml file
* Fixes smaller requests from code reviewers for the previous commit
* This commit is temporary (will be squashed afterwards)

This commit does not (further commits will do though):
* Add global `coverage` entry handling in yml file as suggested by Grzegorz
* Add specs
* Create changelog
* Create docs

* Instead of using the proposed `coverage` key, this expects `coverage_regex`

Create a util for normalizing headers on the frontend

See merge request !8750

Fixed tab index order on branch commits list page

Closes #26447

See merge request !8489

Add metric initializer spec

See merge request !8714

Resolve "Reveal Variables button may overrun width of screen"

Closes #25780

See merge request !8221

Fixing sort of Users so that users who never logged in will be displayed last

Closes #26468

See merge request !8637

adds avatar for discussion note

Closes #26854

See merge request !8734

fix broken image when doing offline update check(help page)

Closes #25982

See merge request !8355

Update buttons on pipelines page to be more accessible

Closes #26445

See merge request !8561

Make the time estimate migrations reversible

See merge request !8749

Dont persist application settings in test env

See merge request !8715

Fix nested tasks in ordered list

Closes #24923

See merge request !8626

Fix typo in link to "Services Templates" page.

See merge request !8709

Add docs for resolve conflicts editor

See merge request !8748

[ci skip]

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

Merge the two 2FA docs into one

See merge request !8747

[ci skip]

An empty file in one of the instrumented directories will cause the app
to fail to start when metrics are enabled. Metrics aren't enabled by
default in development or test.

We could handle the empty file case explicitly, but a file could still
not define the constant it is expected to, so instead run the
initializer manually in a spec and check that it succeeds.