Allow SYSTEM user in Automotive instead of main user.

There are devices where main user is not defined, such as Automotive,
and no uid could pass enforceUid(). Allow SYSTEM user for such cases.

Bug: 285758762

Test: atest com.google.android.gts.persistentdata.PersistentDataHostTest

Change-Id: Ieef580962e12f70ef429ebc2532312a5008167a2
1 file changed