Fix crash in NetworkControllerImpl

Happened due to multiple entry points of configuration changes
running on different threads.

 - Remove the unneeded listening for configuration broadcasts
 - Make the handling for configuration changes happen on the right
   thread
 - Happen to fix the tests :)

Bug: 22560859
Change-Id: I194b4fa233f0a8a33c4ac3252ddec70a93822337