Remove WiFi Monitoring from DcTracker

For longer than I can remember, DcTracker has sat
quietly, vigilantly monitoring the state of WiFi.
For too long have we suffered the sight of wifi
status variables. For too long have we seen the
callbacks firing. No more! From this day forth
DcTracker shall confine itself to the monitoring
of the cellular radio state only.

Bug: 5009624
Test: runtest frameworks-telephony
Change-Id: Ifda6c615e456a346b0f2d694771b28fe8dbeac4c