Clear preferences when dialog acknowledged and increase order

This CL makes it so that the order on the seekbar is increased
to a very large value to ensure it gets added to the end in the
case where a refresh is triggered due to the first time battery
saver dialog. Additionally it clears the preferences on the screen
when we receive confirmation to ensure that no caching can cause
the seekbar ot show up on top of other preferences.

Test: atest BatterySaverScheduleSeekBarControllerTest
Bug: 132107662
Change-Id: I26bf2772ed7135daa4879bca17e0ecfc22a2d0dd