In a call, the flag of UserManager is changed, then "Add user" and "Guest" items in Settings are still enabled. To fix this issue, these items will be disabled according to "UserManager#canSwitchUsers". Bug: 80447394 Test: make RunSettingsRoboTests ROBOTEST_FILTER=UserSettingsTest Change-Id: Ib4c754603418528f5c6f1c78b8aabf33e863c8b9