Bug 2034688

Description of problem:
The openshift/origin test should allow Prometheus/Thanos to return 401 or 403 when the request isn't authenticated.

Version-Release number of selected component (if applicable):


How reproducible:
When CI testing the pull request https://github.com/openshift/cluster-monitoring-operator/pull/1512, the test results of ci/prow/e2e-agnostic, the test "[sig-instrumentation] Prometheus when installed on the cluster should start and expose a secured proxy and unsecured metrics" fails incorrectly: 
This test of calling Thanos querier root URL without authentication should return 401 unauthorized instead of 403 forbidden. The test code sends a request using the curl command curl -k -s -o /dev/null -w 403 https://thanos-querier.openshift-monitoring.svc:9091 without providing any information for authentication. A response with status code 401 should be expected. Same goes for the test "[sig-instrumentation][sig-builds][Feature:Builds] Prometheus when installed on the cluster should start and expose a secured proxy and verify build metrics", too.


Actual results:
The test "[sig-instrumentation] Prometheus when installed on the cluster should start and expose a secured proxy and unsecured metrics" accept HTTP code 403 only.

Expected results:
The test "[sig-instrumentation] Prometheus when installed on the cluster should start and expose a secured proxy and unsecured metrics" accept both HTTP codes 401 and  403.