Revert^4 "libprocessgroup: uid/pid hierarchy for cgroup v2" am: 4dac81680f

Original change: https://android-review.googlesource.com/c/platform/system/core/+/1585101

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Id88c7f5f6b9193af5adc8ebfb19b316c0b2dd938