Do not retry request on EADDRNOTAVAIL.

This errno is caused by IPv6 configuration issues related to Docker.
Since skupperproject#401 fixes this, we can remove this workaround.

tests/system_tests_http.py

@@ -97,8 +97,7 @@ def is_get_request_failing(self, url, use_ca=True, use_get_cert=False):
                 self.get(url, use_ca=use_ca)
             return False
         except OSError as e:
-            # EADDRNOTAVAIL happens in Docker when connecting to localhost:port where nobody listens
-            expected = (errno.ECONNREFUSED, errno.ECONNRESET, errno.EADDRNOTAVAIL)
+            expected = (errno.ECONNREFUSED, errno.ECONNRESET)
             if e.errno in expected or e.reason.errno in expected:
                 return True
             raise e