Revert "Prevent non-admin users from deleting system apps." This reverts commit 9070283638d3f6d80176b073d3cc6e99fdb64e68. Also reverts follow-up CL ag/18185142. Reason for revert: Regression, DELETE_SYSTEM_APP flag no longer works Test: Builds Change-Id: I0c9585c2104488f610a64e6396775a8b6586724a Merged-In: I55a3d322e84aaaced69bd5edeaf90e82ac9a0dd3