Checkable::FireSuppressedNotifications() compares the time of the current
checkable with the last recovery time of parents to avoid notification right
after a parent recovered and before the current checkable was checked.
This commit makes this check also include to host if the checkable is a
service. This makes the behavior consistent with the documentation that states
there is an implicit dependency on the host (which isn't realized as implicitly
generating a Dependency object unfortunately).