Admin - Remove a member from a blob store group spawns threads which are not named contextually

The Admin - Remove a member from a blob store group task spawns threads which have a default name: ie. ForkJoinPool-10-worker-1

Threads and thread pools should spawn threads should be contextually named to aid problem diagnosis in thread dumps. This is something addressed in several different versions of NXRM.

For motivation and context refer to NEXUS-14110 where this was addressed previously in release 3.6.0.

Expected

All thread pools and threads in those pools should be given a name that is relevant to the feature area that is responsible for that pool.

https://stackoverflow.com/questions/6113746/naming-threads-and-thread-pools-of-executorservice