manager: fix connecting to bus when dbus is actually around (#7205)

manager: fix connecting to bus when dbus is actually around (#7205)

manager_connect_bus() is called *before* manager_coldplug(). As a last
thing in service_coldplug() we set service state to
s->deserialized_state, and thus before we do that all services are
inactive and try_connect always evaluates to false. To fix that we must
look at deserialized state instead of current unit state.

Fixes #7146