Changes the text in the Revert merge request modal: `Start a new merge request with these changes` => `Start a new merge request with the revert changes`.

- Fixes thinner right border on the limit box
- Adds and 'elsif' on @Branches for the scenario in which a commit is not related to a branch
- Fixes small details on limit_exceeded_for_message partial

- Improves CSS files by reusing existing code
- Changes logic in views to avoid future problems in translations

- Display the default branch (if the limit is not exceeded)
- Requires '...' to be clicked before showing the rest of the branches and/or tags
- Fixes haml lints

- Create a partial for limit exceeded message
- Modifies specs to adjust new scenarios

- Leave 'too many tags to search' always visible
- Add different message to the branch/tags so it states its unavailable

threshhold, a message is shown indicating we didn't perform the search

since all the signature badge templates now have more or less the same
content we can push most of it down to the main template `_signature_badge`.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/36804

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