Let setPersistentActivity() fail if it can't find the display

- With getDisplayContentOrCreate(), it can cause the system crash when
  the race-condition happens for the newly added virtual display.
- It would be better to let the api fail when the race-condition
  happens.
- Adjusts some log messages.

Bug: 262743998
Test: atest com.google.android.car.ats.CarActivityManagerTest#testSetPersistentActivity
Change-Id: I12e120016bc75da699db2f7081f7a751ef751abc