3scale QE automated test test_referrer_policy.py fails when running on RHOAM.

This test ensures referer apicast policy works as expected and manipulates with Referer header (it uses 'localhost' and 'localdomain' values for testing purposes).
apicast returns 403 for some reason - maybe referer header isn't set in the request (is it possible envoy does some manipulation with headers?)
This test does pass with standard 3scale deployment.
This test did pass with previous RHOAM versions.

HOW to investigate

Only 2 jiras related to 3scale in this release  

 - MGDAPI-4707 mas stream

 - MGDAPI-4749 bump off 3scale-openshift service mesh

1) We need to determine which of the 2 changes caused the issue. Verify with 3scale if the same test passed during the mas stream testing.

2) Provision a cluster with  MGDAPI-4749 reverted and re run the test. Run the test ourselves if straight forward. Otherwise request 3scale to run the test.

Another possibility....

Is that this issue has existed in RHOAM for a while as there was a bug whereby requests to apicast were bypassing envoy. this is now fixed. To rule this out we could bypass envoy and rerun the test:

how: go to apicast services and change target port to 8080 from 8443 but scale down rhoam operator first

Related JIRAs: https://issues.redhat.com/browse/MGDAPI-3878 && https://issues.redhat.com/browse/THREESCALE-8385