Fix visibility bugs in QS user detail panel

- Fix bug that prevented user from accessing QS user panel using Switch
  Control

- Fix bug that caused QS user panel to sometimes not show

Bug: 184072778
Bug: 182404283
Test: Build with config_keyguard_user_switch_opens_qs_details=true, turn
      on Switch Control, navigate to QS user panel from the lock screen,
      add guest user
Test: Build with config_keyguard_user_switch_opens_qs_details=true,
      unlock phone, open QS, lock phone, tap QS user panel shortcut on
      lock screen
Change-Id: Idbf04e77a01b741d2ecd8d5db863cdf0bc5cedbc