After filtering Permissions Hub by permission, make the back button return to the unfiltered view.

Previously, filtering by a permission group simply changed the filter
in the current fragment.  Thus pressing the back button returned to
the previous screen instead of undoing the filter.  This changes that
behavior.

Also update the string for removing the filter.

Fixes: 129415632
Test: Open Permissions Hub, filter by group, press back, see
Permissions Hub.
Test: Open filtered view, press "See all", press back, see filtered
view.
Test: Launch filtered view initially, press back, return to parent.
Change-Id: Id77b24bb30986ddbe8826297cd2d6187f1786a41