[SSSD] [sssd PR#5784][comment] proxy: allow removing group members

[ikerexxe]

URL: https://github.com/SSSD/sssd/pull/5784
Title: #5784: proxy: allow removing group members

ikerexxe commented:
"""
Ready for a new rounds of reviews.
"""

See the full comment at https://github.com/SSSD/sssd/pull/5784#issuecomment-948683748