Add retry on RuntimeError while connecting to api server

While connecting to API server, the library could raise RuntimeError if
authentication fails. During system init, it is possible that keystone server is
not yet up. We should retry on such failure.

Change-Id: I2cc84c1d6fbd3e78fb6cb42d3c21944b54c0061b
Closes-Bug: 1477907
(cherry picked from commit 44fe58f7857fb33020412e9b0bd832f505eb3978)
(cherry picked from commit e6112b9)

src/config/schema-transformer/to_bgp.py

@@ -3940,7 +3940,8 @@ def connection_state_update(status, message=None):
             # Update connection info
             connection_state_update(ConnectionStatus.DOWN, str(e))
             time.sleep(3)
-        except ResourceExhaustionError:  # haproxy throws 503
+        except (RuntimeError, ResourceExhaustionError):
+            # auth failure or haproxy throws 503
             time.sleep(3)
 
     global transformer