Update metrics-collector/prometheus.yml.template

Co-authored-by: Norman Böwing <9320860+norman465@users.noreply.github.com>

Author: reggeenr

metrics-collector/prometheus.yml.template

@@ -80,6 +80,7 @@ scrape_configs:
     - action: labeldrop
       regex: "serving_knative_dev_(.+)"
     # drop default prometheus labels
+    metric_relabel_configs:
     - action: labeldrop
       regex: "instance"
     - action: labeldrop