Track merge requests of cherry-picked commits when deploying
In https://gitlab.com/gitlab-org/gitlab/issues/36130 we tracked the first implementation of MR cherry-pick tracking.
[Issues board](https://gitlab.com/groups/gitlab-org/-/boards/1685330?scope=all&utf8=%E2%9C%93&state=opened&epic_id=26352)
Here we can track all the follow-up items
## :hourglass_flowing_sand: In progress
* Clean up deployment_merge_requests without environment_id - https://gitlab.com/groups/gitlab-org/-/epics/2764
* backfill deployment_merge_requests.evironment_id with a background migration - https://gitlab.com/gitlab-org/gitlab/issues/208905
## :next_track: Next
* Clean up deployment_merge_requests without environment_id - https://gitlab.com/groups/gitlab-org/-/epics/2764
* Don't allow null on deployment_merge_requests.environment_id - https://gitlab.com/gitlab-org/gitlab/issues/208906
* Once we collect a bit of real data, consider detecting cherry-picks from Git command line: https://gitlab.com/gitlab-org/gitlab/issues/202215
## :white_check_mark: Completed
* Cherry-pick tracking: https://gitlab.com/gitlab-org/gitlab/issues/36130 - https://gitlab.com/gitlab-org/gitlab/merge_requests/22209
* define a proper icon for the feature: https://gitlab.com/gitlab-org/gitlab/issues/202212 & https://gitlab.com/gitlab-org/gitlab-design/issues/965
* A cherry-picked MR will be tracked as deployed twice: https://gitlab.com/gitlab-org/gitlab/issues/199256
* remove `track_mr_picking` feature flag - https://gitlab.com/gitlab-org/gitlab/issues/199044
## :video_camera: demos
* [Feature demo](https://youtu.be/CkSbp5A_SsY)
epic