Fix SystemUITests:FooterActionsViewModelTest.

Bug: 423011184
Flag: EXEMPT - test behavior should be independent from flag state.
Test: adb shell aflags disable android.app.supervision.flags.enable_supervision_app_service && adb reboot && atest SystemUITests:com.android.systemui.qs.footer.ui.viewmodel.FooterActionsViewModelTest; adb shell aflags enable android.app.supervision.flags.enable_supervision_app_service && adb reboot && atest SystemUITests:com.android.systemui.qs.footer.ui.viewmodel.FooterActionsViewModelTest
Change-Id: Ic8772ba3b83ae8e497b924427d269b5bb0942108