Update/fix SensitiveContentProtectionManager test

- Use real MediaProjectionInfo, not a mock
- Fix failing tests from recent change that does not update wm with
  empty set of packages

Bug: 332782679
Test: atest SensitiveContentProtectionManagerServiceNotificationTest
Flag: N/A - test fix
Change-Id: I3d1ce2c487abece12016ec4ad08e7d0f31e25172