Revert "Grant the ACTIVATE_PLATFORM_VPN appop if VPN app has CON..."

Revert submission 2141595-GRANT_PLATFORM_VPN

Reason for revert: Refer to the comment in ag/19491935.
Reverted Changes:
I0e0566bb8:Grant the ACTIVATE_PLATFORM_VPN appop if VPN app h...
I0580baca6:Test if VPN app can grant ACTIVATE_PLATFORM_VPN wi...

Change-Id: I6cfdd2b75aa6e7427ffa6024e1c3ff183a3e0379