Make seekbar static when animations are disabled

Listen to updates to the animation duration setting, which will be set
to 0 when the accessibility option to remove animations is true, and
disable the wavy seekbar animation if so

Fixes: 226987432
Test: atest MediaControlPanelTest SeekBarObserverTest
Test: visual - verify seekbar animation follows a11y setting
Change-Id: I8ec4115e5c803f066b804642c524f9e4ebd38c5e