Revert "Prevent non-admin users from deleting system apps."
This reverts commit 6c870e15.
Reason for revert: Regression, DELETE_SYSTEM_APP flag no longer works
Change-Id: Id3eb9e08a5404e88c39235d0d47337ed41bc6139
Merged-In: I4e959e296cca9bbdfc8fccc5e5e0e654ca524165
(cherry picked from commit d9089fbe)
Merged-In: Id3eb9e08a5404e88c39235d0d47337ed41bc6139