[Provider Model] Adjust slice title and subtitle

- Show "Airplane mode" title when airplane mode is enabled

- Remove "Airplane mode is on" subtitle

- Show "Wi-Fi is turned on" subtitle when both airplane mode and Wi-Fi
is enabled

- Remove the function related to isApmNetworksAvailable()

- Screenshot:
  https://screenshot.googleplex.com/6X9nzmXRCUfw4Lp
  https://screenshot.googleplex.com/6jQryMjU2yDDpmM

Bug: 181858434
Test: manual test
atest -c InternetConnectivityPanelTest \
         InternetPreferenceControllerTest \
         InternetUpdaterTest

Change-Id: I84e5d4c60ed91d58443b27c35286a84bf72ac173