To allow unit tests to run without platform certificates, remove
signature permission usage in ConnectivityServiceTest.
This mocks permission checks done in ConnectivityService for which the
test assumed that the permission was held, and mocks calls to
BatteryStatsManager. Calls to ActivityManagerService (through
PendingIntent) are done with shell permissions as the test uses real
PendingIntent mechanics.
Bug: 187935317
Test: atest FrameworksNetTests:ConnectivityServiceTest
Change-Id: I80c5cae5fcd3d40be55d1a79a93d614e665fbbf4
bba8ec0d43