Can no longer order merge requests by merge date.
## Steps to reproduce:
1. Build a feature
2. Have two or more merge requests to a `develop` branch
3. Need to cherry-pick in order of merging to `main`
## What should happen:
1. I go to the MR search
2. I filter by a certain label (`Pending cherry-pick to main`)
3. I order by merge date
4. I cherry-pick the MRs in the right order
## What happens instead
1. I go to the MR search
2. I filter by a label
3. I **cannot** order by merge date
## Extra information
- Bookmarked URL: `https://gitlab.{selfhosted.domain}/dashboard/merge_requests/search?author_username=mdemaa&scope=all&sort=merged_at_desc&state=merged`
- This was previously possible
- I’m aware of the new “Merged” tab, but this doesn’t allow me to filter by a label
issue