Keep the implicit flag for pre-23 apps when inheriting implicit

permissions

A subset of permissions don't get the implicit flag (REVOKE_ON_UPGRADE)
when inheriting state from their source permissions. However,
that should not apply to pre-23 apps because for them the
implicit flag means REVIEW_REQUIRED instead of REVOKE_ON_UPGRADE.

Bug: 346721675
Flag: EXEMPT bugfix
Test: atest PermissionFlagsTest SplitPermissionTest
Change-Id: I58608af39643b94db0baac5307d5335f6734629e