Properly test TrafficController permissions on package updates.

The current test we have for a package changing TrafficController
permissions (i.e., INTERNET or UPDATE_DEVICE_STATS permissions)
is not realistic.

This is because the test simulates the update by removing and
adding the package. But TrafficController permissions are not
driven by broadcasts, they are driven by PackageListObserver,
and when an app is updated, PackageListObserver does not see a
remove and and add, but a single change event.

Add a new test for this.

Bug: 137864893
Test: new unit test added
Change-Id: I691b928f57c79c19dfb6ddb01983d55ef305c472