Fix issue where AllAppsContainerView was blocking touches to part of the home screen

=> After the scrubber was engaged, it would continue to intercept touches forever
   (seems like a long standing issue)
=> Also fixed issue where the All Apps scrubber could be engaged from the Home / Overview
   states

b/133265591
b/132716177

Change-Id: I8c7b9d45be65216f2f1a69f69ab1636accd812c0