Update tests to support floating search.

Tests need to be updated to account for the new placement of the
searchbar because it overlapped with touch events for scrolling:
 - Scroll back to top: Instead of scrolling from the top of the
   container which could overlap status bar in landscape, scroll
   from the bottom of the top-most visible app icon.
 - Scroll down: swipe up from bottom padding to top of top-most
   visible icon.
 - Close all apps: swipe down more quickly from top icon insetad
   of the search bar (more quickly helps it be detected as a
   fling on more cramped devices).

For Launcher3, the floating flag is not fully supported yet, so
there were some layout issues which are now resolved by ignoring
the flag if the searchbar is still at the top.

Fix: 268052768
Test: Ran tests, manual
Change-Id: If54717e2835c7cc4ed1368554bbc493193945c1d
Merged-In: I406fbcbe12acddb1dd4b862a380576a48cabbebc