Downgrade Azure provider "Failed to extract" log to debug

When running the Azure provider at default log level, this messages
is 1/min and is the only messge in the log. Debug seems more
reasonable and matches what Azure Private provider.

provider/azure/azure.go

@@ -119,7 +119,7 @@ func (p *AzureProvider) Records(ctx context.Context) (endpoints []*endpoint.Endp
 			}
 			targets := extractAzureTargets(&recordSet)
 			if len(targets) == 0 {
-				log.Errorf("Failed to extract targets for '%s' with type '%s'.", name, recordType)
+				log.Debugf("Failed to extract targets for '%s' with type '%s'.", name, recordType)
 				return true
 			}
 			var ttl endpoint.TTL