Update e2e test selectors for lock screen user switcher

Also removes "InputArea" test tag that is not used anywhere, this is overriding the test tag added inside the InputArea composable

Bug: 310005730
Flag: com.android.systemui.compose_bouncer
Test: atest PlatformScenarioTests:android.platform.test.scenario.sysui.multiuser.MultiUsersUiTest#testMultiUsers_shouldHaveMultipleUsersInExpandedList -- --abi arm64-v8a
Change-Id: I89cdc28fe89cda84016d6f2f099b0321a72ff606