core: re-sync bus name list after deserializing during daemon-reload

core: re-sync bus name list after deserializing during daemon-reload

When the daemon reloads, it doesn not actually give up its DBus connection,
as wrongly stated in an earlier commit. However, even though the bus
connection stays open, the daemon flushes out all its internal state.

Hence, if there is a NameOwnerChanged signal after the flush and before the
deserialization, it cannot be matched against any pending unit.

To fix this, rename bus_list_names() to manager_sync_bus_names() and call
it explicitly at the end of the daemon reload operation.