Improved Autofill logging.

- Removed ui.Helper.
- Replaced DEBUG and VERBOSE constants by sDebug and sVerbose.
- Added a shell command to dynamically set the constants.
- Removed obsoleted log statements.
- Changed log-level of some log entries.
- Removed unused methods.

Fixes: 36141126

Test: CtsAutoFillServiceTestCases pass
Test: manual verification

Change-Id: Ic08ee9a2adc10e63f49bbcc7ed126455462dc9c1