Thanks to T264343 / structured mentor list, we now have an "umbrella API endpoint" to manage information about mentors. Once the structured mentor list gets deployed (T310905), we should replace `action=growthsetmentorstatus` with `action=growthmanagementorlist`.
Checklist:
[X] Complete {T321502}
[X] Remove all internal callers of `action=growthsetmentorstatus` ([r936090](https://gerrit.wikimedia.org/r/c/mediawiki/extensions/GrowthExperiments/+/936090))
[X] Mark `action=growthsetmentorstatus` as deprecated, pointing users to `action=growthmanagementorlist` instead ([r936090](https://gerrit.wikimedia.org/r/c/mediawiki/extensions/GrowthExperiments/+/936090))
[X] Announce change via #user-notice ([draft announcement](https://meta.wikimedia.org/w/index.php?title=Tech/News/2023/29&diff=prev&oldid=25297423))
[X] Wait a week & check for usages.
[ ] If possible, remove code supporting `action=growthsetmentorstatus`. Alternatively, re-announce and remove later.