Change to getSystemService(Class<T>) to align the capability with framework
part.
Bug: 179640862
Test: local
Change-Id: I1b4812044fc4876bec6645570049a60f9470dbbd
Connectivity is becoming a mainline module in S, so
ConnectivityManager hidden symbols can not be used for outside
components. Besides, most Tethering relevant methods or variables
on CM are migrated to TetheringManager. So replace all these
methods or variables from ConnectivityManager to TetheringManager
on Settings.
Bug: 180693313
Test: make RunSettingsRoboTests ROBOTEST_FILTER=<Modified Test>
Change-Id: Iba4b121a4ddf3f04252aa0355e0e6494a593682a
Merged-In: Iba4b121a4ddf3f04252aa0355e0e6494a593682a