Resolve "Expand 'Related Branch' detection"

What does this MR do?

This MR is related to #29948

This regex will allow the detection of a issue related branch inside grouping branches, something like this:
1234-relevant-branch-name
feat/1234-relevant-branch-name
milestone/feat/1234-relevant-branch-name
And so on.

I'm not sure if/where do I need to modify the spects to validate this behaviour.
I remember reading about this behaviour in the docs but can't seem to find it.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.

Closes #29948