Remove "Go Back" option from verify root and recovery options

These options only show when you are exiting recovery and there
is no where to "go back" to.

Patchset 1) initial
Patchset 2) change to ui_set_showing_back_button()
Patchset 3) revert settings before returning

Change-Id: I0aee8d0fbce9a5ff415b74b4a16e0d416042e307
Merge "Remove "Go Back" option from verify root and recovery options" into cm-11.0