Fix #5918

The method clean_dashboard_address will also return an empty string. In this case the start_address should be used which will account for the "host" parameter used when specifying a Cluster

This will fix the bug a firewall popup will be created even if `Localcluster(host=localhost)` is specified

distributed/node.py

@@ -145,7 +145,7 @@ def start_http_server(
         http_addresses = clean_dashboard_address(dashboard_address or default_port)
 
         for http_address in http_addresses:
-            if http_address["address"] is None:
+            if http_address["address"] is None or http_address["address"] == '':
                 address = self._start_address
                 if isinstance(address, (list, tuple)):
                     address = address[0]