ThemeManager: Needs to use android.uid.system

The android.uid.system needs to be used for devices using a selinux kernel.
This should not cause issues with any other devices with non-selinux kernels.

Change-Id: I04d748d440ebafecbe94343a029c186a180ef13c
Revert "Fixed some crash-on-theme-removal scenarios"

This reverts commit a80fb9582f8808d92b4e8727ab9b6bc5958b58b8.

Change-Id: Id91f81eea197f9d56327fd16f2d5ba6e7999999f