Use SetProcessProfilesCached in android_os_Process_setProcessGroup

Currently, android_os_Process_setProcessGroup uses SetTaskProfiles for
each thread of a process when switching group, which will hold lock each
time. Replace it with SetProcessProfilesCached so that it only does it once.

Bug: 215557553
Test: cgroup migrates as expected
Change-Id: I0ebb031a395932c269e88e52faed1661bbf8420a