TCMS: Trust the package name for requests by the system.

Bug: 129333710
Test: (MANUAL)
 - Select text that is an entity e.g. 8pm in an app
 - Go to Settings -> Apps -> See all apps -> More options -> Show system ->
   Actions Services -> Force stop
   (Note that the system will always restart this process as it hosts
   the TCS)
 - Return to the app with the selected text (reselect text if necessary)
 - Ensure that adb logcat -b system | grep "Invalid pacage: name=" isn't
   logged.
 - Retry the above sequences a few times.
Test: atest android.view.textclassifier

Change-Id: I6ab2abf9d9604d4b6a70634ad9d417214b61608e