Do not show track when scrubing when notification shade is down

Prevents drawing quick scrub track when notification shade is down. Also
allow the KeyButtonView touch events to be passed when notification
shade is down to show ripple.

Test: bring notifications down and swipe the home button to the right
Change-Id: I386e45f9f164e39bbba6baa86a881e1351940f7e
Fixes: 73667292