Disable home control dream when flag disabled

This is disabled by default, but its possible that the flag flips from
true to false, in which case we should disable the service again the
next time we boot up. This prevents the flag state in sysui from
becoming out-of-sync with the flag state in WM.

Bug: 328312051
Flag: ACONFIG android.service.controls.flags.home_panel_dream TRUNKFOOD
Test: atest SystemUiRoboTests:HomeControlsDreamStartableTest
Change-Id: I71d3f60eb542d5dcf2352f89ce1f801a4246aee1