Lower missing metrics error to a warning (#992) (#1035)

Author: Andrew-Lees11

internal/metrics/update.go

@@ -175,7 +175,7 @@ func initialiseMetrics(log *logger.Logger) (map[string]*metricData, error) {
 							log.Debugf("Metrics: Skipping metric, metric is not enabled for key [%s]", key)
 						}
 					} else {
-						log.Errorf("Metrics Error: Skipping metric, unexpected key [%s]", key)
+						log.Printf("Metrics Warning: Skipping metric, unexpected key [%s]", key)
 						validMetrics = false
 					}
 				}