Recently while working on MediaWiki-extensions-SecurePoll, AHT encountered a use-case which can best be fulfilled by having a user-group that includes all staff accounts. More context for the specific issue in T180762#6842624. I can imagine there are other times when there are WMF-staff-specific use cases for product teams which are currently difficult to fulfill.
This task is to create a user-group for all WMF staff accounts and have a way to keep the group up-to-date with new account creations.
Note that there is an existing user-group called staff which serves a different purpose. In the interest of time, we should make this new user group be staff-all or something to avoid a renaming process for the old user-group first.