Remove methods from MainHandler.

Followup from ag/3516264 where callbacks are now already invoked on the
main thread. There is no reason to execute this methods on the
MainThread. Removing UPDATE_ACCESS_POINTS in following CL as it has more logic
in that requires careful modification.

Also make changes to how verbose logging is determined (now respects
logging tag as well as developer option) and log callbacks.

Bug: 37674366
Test: runtest --path
frameworks/base/packages/SettingsLib/tests/integ/src/com/android/settingslib/wifi/WifiTrackerTest.java

Change-Id: I373af3a65596d478ec25bd2c67a41fc3c7033beb