Merge "Revert "libprocessgroup: Add a function to remove only empty process...

Merge "Revert "libprocessgroup: Add a function to remove only empty process groups"" into main am: ced62e53 am: 926f3dd2 am: f8628885

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2829574



Change-Id: I63db6efd42ad3f5214a6c38d568e0c10793d8c97
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>