Don't show "Save guest activity?" dialog after "Reset guest" is chosen

Bug: 339171511
Test: atest UserSwitcherInteractorTest#removeGuestUser_shouldNotShowExitGuestDialog
Test: atest UserSwitcherInteractorTest#resetGuestUser_shouldNotShowExitGuestDialog
Test: After turning of "Settings -> System -> Users -> Delete guest
      activity", manually switch to a guest user second time and
      select "Reset guest" from the notification. And observe
      "Save guest activity?" dialog is not shown anymore.
Flag: None
Change-Id: Ic7c0ea75715421f8923a538f482d20aa52549635