The test can't have TetheringManager as an argument to methods or a
field, otherwise the test runner will crash when scanning the class for
tests because TetheringManager did not exist in Q. Although
testFactoryReset is already skipped on Q, the test runner would fail
at initialization time, before starting the run.
Use CtsTetheringUtils instead. This ensures that TetheringManager does
not have method signatures or members that reference classes that do not
exist on Q, so the test runner can scan the class successfully before
starting the run.
Bug: 188851796
Test: atest ConnectivityManagerTest on Q
Change-Id: I87488d0f23628a1ef2d7af0242513fcc5401d598
0d54d7992d