Stop disabling supervision when the supervision app is not the PO.

Now there's a switch in Settings that is capable of turning on supervision independently from PO.

Bug: 381428475
Test: atest SupervisionServiceTest
Flag: android.app.supervision.flags.enable_sync_with_dpm
Change-Id: I2a427cde8a81c19b28948b4e6b4c24c76a0eaf12