1. Proposed title of this feature request

Allow overwriting of prometheus_replica in prometheus remotewrite

2. What is the nature and description of the request?

Customer uses remote_write to send logs to external metric store. The external metric store deduplicates (since we have 2 prometheus pods each sending metrics, this is necessary to prevent double the metrics). However, their particular solution does not deduplicate unless every field is duplicate, so the prometheus_replica field breaks this. They previously overwrote this field with an externallabels value of prometheus_replica: "", but this is no longer possible in 4.16.

We tried adding this to the remoteWrite config but it did not work (presumably the operator overwrote us):

   - action: labeldrop
     regex: prometheus_replica

4. List any affected packages or components.

Prometheus Remote Write