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
2 files changed