wifi(vts): Use blocking getService to wait for service to come up

Switch away from using wifi's custom implementation to block for
supplicant/hostapd daemon to come up.

Bug: 161682236
Test:
vts-tradefed run commandAndExit vts --module VtsHalWifiHostapdV1_0Target
vts-tradefed run commandAndExit vts --module VtsHalWifiSupplicantV1_0Host

Change-Id: Ia05f93ba4a28c036315558edbba30f19c2e6ac95