Updated gesture navigation tutorial.

- Removed 'x' button and added tappable 'skip' text to exit the tutorial.
- Updated tutorial step indicator
- updated AVD colors.
- removed unused AVDs
- Increased the visible duration of the feedback view

Test: Manual
Bug: 148542211
Bug: 169687177
Change-Id: Ice61b1273ff270b068d008b5259d100c66057478