Create index asynchronously for merge_request_metrics
What does this MR do and why?
Related to !140002 (merged)
The ability to filter merge requests by merge_user (merged_by_id
column in merge_request_metrics
table) needs an index to be usable in production with large datasets.
@ghavenga ping ;)
I'd also like to submit additonal queries for testing to verify that this index is used in some special filter combinations.