Display regex pattern instead of "Specific branches" label
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Relates to https://gitlab.com/gitlab-org/gitlab/-/merge_requests/102499#note_1257415535
> When we setup specific branches mirroring, we don't show which regex is used for it

## Proposal
Display regex pattern in the list of mirrored repositories.
Alternatively have a way to view what the pattern is in an edit view. This solution may be more involved as it might require an edit view.
issue