What does this MR do?
Refresh the MR counter cache after merging an MR.
Are there points in the code the reviewer needs to double check?
Don't think so.
Why was this MR needed?
We did this on every MR state change event except a merge, so if the last change to an MR's state was a merge, the counter would be wrong.
Does this MR meet the acceptance criteria?
Changelog entry added, if necessary
Tests added for this feature/bug
Has been reviewed by Backend
Conform by the merge request performance guides
Conform by the style guides
Squashed related commits together