Pre-fixup for nav up button

- Remove SettingsDrawerActivity.EXTRA_SHOW_MENU and force up nav button
  to always show. The button doesn't do anything yet. It just finishes
  current activity.
- Remove dead code about suggestions

Change-Id: I61fa9fefbaa9bced841a05969544b1c824c564ce
Bug: 72337421
Test: rebuild