Remove DevelopmentTileConfigActivity and clean up fragment.

- The tile activity is internal to Settings and nobody should launch it
  externally, thus it doesn't need to have its own activity. Preference
  framework can launch the fragment as a SubSetting

Fixes: 67603649
Test: robotests
Change-Id: I9ba2fc55eb7f571f816ec045567f2dd2714c44e8