Fixed an issue where heads-upped notifications would stay

If a heads up notification was briefly removed right after
it was added it could linger around in systemUI until
the panel collapsed.
We need to make sure not to apply this improvement if
reordering isn't allowed, otherwise it will never time out

Test: existing tests pass
Bug: 34608075
Change-Id: I7768f6111ada30edcb997a42940e5e336efe1cf2