Ensure cgroup.procs in the same cgroup (#2)

cgroup is managed by AMS, when AMS change cgroup of a task, it
ignored other processes in the same process group
if a foreground app call fork at JNI and then switch to background,
children processes will keep foreground priority and out of control

dex2oat is a real world example that foreground app call exec dex2oat to
compile dexfile, when the parent process switch to background cgroup,
dex2oat will not follow it, foreground cgroup allows background dex2oat
hold huge of CPU resources, it may impact UX of foreground apps

Properties to control:
ro.vendor.qti.cgroup_follow.enable to enable/disable this feature
ro.vendor.qti.cgroup_follow.dex2oat_only to use for all or dex2oat only

CRs-Fixed: 2139112

Change-Id: I890a11468a4e419a20611ab5f48de2720ed20e15