Before, this would:

1. Not use the correct reference for non-JIRA external trackers.
2. Append 'Closes ' if an external tracker was enabled, but no issue matched the
   branch name.

Closes #26466.

When JIRA or Redmine were enabled and the branch name did not match the
matching regular expression, the `issue_iid` would be `nil`, preventing
users from creating merge requests.

Closes #43193

Merge branch 'security-10-4-25223-snippets-finder-doesnt-obey-feature-visibility' into 'security-10-4'

[Port for security-10-4]: Makes SnippetFinder ensure feature visibility

Uses Lfs::FileModificationHandler to coordinate LFS detection, creation of LfsObject, etc

Caveats:
 1. This isn't used by the multi-file editor / Web IDE
 2. This isn't used on rename. We'd need to be able to download LFS files
    and add them to the commit if they no longer match so not as simple.
 3. We only check the root .gitattributes file, so this should be improved
    to correctly check for nested .gitattributes files in subfolders.

Currently we still need to run EnsureStageService within a transaction,
because when it runs within in a transaction we are going to stick to
the primary database when using database load balancing. Extracting this
out of the transaction makes it possible to hit into problems with
replication lag in pipeline commit status API, which can cause a lot of
trouble.

We stop relying on Gitlab::Git::Env for the RevList class, and use
Gitlab::Git::Repository#run_git methods inteaad. The refactor also fixes
another issue, since we now top using "path_to_repo" (which is a
Repository model method).

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

Adds `#build_notification_recipients` to `NotificationRecipientService`
that returns the `NotificationRecipient` objects in order to be able to
access the new attribute `reason`.

This new attribute is used in the different notifier methods in order to
add the reason as a header: `X-GitLab-NotificationReason`.

Only the reason with the most priority gets sent.