This will allow EthernetManagerTest to include test interfaces as
NCM-only interfaces.
Note that at this point, setting any TEST_INTERFACE_MODE includes a
test interface in both MODE_ETHERNET and MODE_NCM (equivalent to
setIncludeTestInterface(true)) as the mode is not propagated further
than EthernetServiceImpl.
Test: TH
Flag: EXEMPT mainline
Change-Id: I52a36ebb29bc27a21c7521c1cd9bd186001ac6c5
6822c19294