daemon: Suppress logging of VIR_ERR_NO_DOMAIN_METADATA

Similarly to other error codes that notify the user that the object does
not exist lower the priority of VIR_ERR_NO_DOMAIN_METADATA to
VIR_LOG_DEBUG when writing the log entry.

daemon/libvirtd.c

@@ -320,6 +320,7 @@ static int daemonErrorLogFilter(virErrorPtr err, int priority)
     case VIR_ERR_NO_SECRET:
     case VIR_ERR_NO_DOMAIN_SNAPSHOT:
     case VIR_ERR_OPERATION_INVALID:
+    case VIR_ERR_NO_DOMAIN_METADATA:
         return VIR_LOG_DEBUG;
     }