Fixing up the tests.

- Recent change b35ab019 changed the prefix highlight colour but didn't
  update the test.  This fixes the test.
- ContactUtils.areObjectsEqual() method is no longer in use, so was being
  removed by Proguard, causing the test to fail.  The method may be useful
  in the future, annotated it with @NeededForTesting.
- Some setTextWithHighlightingFactory... methods in both
  DisplayNameFormatter and ContactListItemView were not being used any
  longer, only by the unit tests that tested them.  Proguard was therefore
  removing them, causing the tests to fail.

Change-Id: I8e52a6d4dc7eac398777897b38cad4ef44d4fa7d