These controllers extended AbstractPreferenceController, which is not quite compatible with some of the present framework. Especially for indexable keys of settings search. TetherEnabler and AllInOneTetherSettings are refactored based on the change. Tests are updated. Bug: 147272749 Test: CodeInspectionTest and other tests of classes touched by this CL Change-Id: Ic3ad13e735d133c0959a0a309319a6fd5165b015