Update mocking to correct target methods

The correct target context should use the mActivity in
MobileNetworkSettingsTest, so that the mocking for
telephony service could correctly applied.

Both AutoTimeZonePreferenceControllerTest and
BasebandVersionPreferenceControllerTest refer to the lib
implemented shadow Connectivitymanager but that does not
the correct reference after utils class being updated.
Update the test logic inside to refer to correct method.
The reference to ShadowConnectivityManager does not needed
anymore so remove it from the test.

Fix: 183068151
Fix: 183067742
Fix: 183068139
Test: make RunSettingsRoboTests ROBOTEST_FILTER=\
com.android.settings.network.telephony.MobileNetworkSettingsTest
Test: make RunSettingsRoboTests ROBOTEST_FILTER=\
com.android.settings.datetime.AutoTimeZonePreferenceControllerTest
Test: make RunSettingsRoboTests ROBOTEST_FILTER=com.android.settings\
.deviceinfo.firmwareversion.BasebandVersionPreferenceControllerTest

Change-Id: I15ecc6aab7d530d20cd23b06267cc184a2c62b40