Before this change the test assume one active state event is followed by
zero or one availabe event:
AVAIALBE(wlan1) -> ACTIAVE(wlan1) -> AVAILALE(wlan1)
But actually Multiple tetherable wifi interfaces may be avaialbe during
the test:
AVAILABLE(wlan1) -> AVALIABLE(wlanX) -> .... -> ACTIVE(wlan1) ->
AVAIALBE(wlan1)
Additional, replacing ConnectivityManager usage to TetheringManager.
Bug: 148095484
Test: atest CtsTetheringTest
Change-Id: Id5db970c02f63f61802a18b599bf6905db619b42
cdd2b36062