Define relationship of UX Manager and Usability topic maintainers

I’d personally remove the Usability topic maintainer and move the responsibility to the UX Manager, since Usability is a part of UX and it feels complicated to keep a role that only review Usability for specific screens without taking into account the whole experience.

I wouldn't remove the tag "Needs usability review" since it's useful to tag issues that need an smaller review and can be done by several contributors without the need to get a UX Manager review. I'd create the "Needs UX Manager review" or similar for bigger changes that impact the user experience more broadly, beyond specific small UX copy-writing or UI changes, like changes that impact flow changes or several systems.

Agree with @ckrina, I think UX Manager incorporates the role of the Usability topic maintainer and it's confusing to have both. "Needs usability review" tasks relating to small changes could potentially be picked up by volunteers in the UX, UI and design contributor community role

The current usability maintainers are as follows (from MAINTAINERS.txt):

Usability
- Cristina Chumillas 'ckrina' https://www.drupal.org/u/ckrina
- Roy Scholten 'yoroy' https://www.drupal.org/u/yoroy
- Bojhan Somers 'Bojhan' https://www.drupal.org/u/bojhan

Roy and especially Bojhan have not been active in years. It would be true to reality I think to remove them anyway, which leaves Cristina. At that point, we don't have dedicated Usability maintainers other than the UX manager which Cristina is being assigned to already.

Cristina landed as UX Manager in 📌 Add Emma Horrell as UX Manager to Drupal core Active now.

The changes are in line with what has been discussed: this clarifies the responsibilities of the UX Manager and keeps the “Needs usability review” tag because it’s a process / review needed regardless. Plus it clarifies how to use the “Needs UX Manager review” tag for changes that need sign-off.