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: 9b631cb3 am: c3d17850

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



Change-Id: Ic62d3b1816d55b1ff6d295000dc2c5ee107397f3
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>