Reduce log spam in GameManagerService.

Since it is possible that DeviceConfig returns packages that haven't
been installed, the query will fail in those cases. Avoid logging
exception in this case.

Minor: clean up some logs.

Fixes: b/187741764
Test: atest GameManagerServiceTests
Change-Id: I08a48da82761b5a902a09f18a8b88eb0281f892b