Automatically trigger OomAdjuster updates for Backup

Coincidentally this will also fix the out of order update triggering in
the Backup stop path.

Flag: com.android.server.am.push_global_state_to_oomadjuster
Flag: com.android.server.am.auto_trigger_oomadj_updates
Fixes: 369300367
Bug: 399666866
Test: atest MockingOomAdjusterTests

Change-Id: Ie784387a4afa871dcb79fd304630e36dc7e9521e