Batch Service related PSC updates

The ProcessStateController BatchSession will prevent any OomAdjuster
update from being triggered until the BatchSession is over. Throughout
the Service management code are nested methods that may trigger
OomAdjuster updates and result in many unnecessary back to back
updates. Wrapping high level flows with a BatchSession will collapse
all attempted update triggers into one large update that handles all
processes being updated.

Flag: com.android.server.am.psc_batch_service_updates
Bug: 437171290
Test: atest android.app.cts.service.ServiceTest
Change-Id: I4e2357b808e86806f555b34cc237324e84a718bd