replica-conncheck: log when failed to RPC connect

It's nearly impossible to find out what happened when doing
replica connection check and it fails during the RPC phase.
The error is now logged.

Reviewed-By: Martin Basti <mbasti@redhat.com>

install/tools/ipa-replica-conncheck

@@ -586,7 +586,8 @@ def main():
                     finally:
                         if api.Backend.rpcclient.isconnected():
                             api.Backend.rpcclient.disconnect()
-            except Exception:
+            except Exception as e:
+                logger.debug("RPC connection failed: %s", e)
                 logger.info("Retrying using SSH...")
 
                 # Ticket 5812 Always qualify requests for admin