Wrong response code 200 although cx_warning in response header

**Steps to reproduce:**
- Start docker-compose.yaml however without the provider agent started
- Send request like
curl --location 'http://localhost:8102/api/agent?asset=http%3A%2F%2Ftiera-control-plane%3A8282%23SkillAsset%3Fsupplier%3DTraceIncidentSite&incidentSite=BPNS000004711DMY' \
--header 'Content-Type: application/sparql-results+json' \
--header 'Authorization: Basic Zm9vOg=='

**Expected result:**
Response code is 203 as there is a cx_warning in the response header pointing to the missing provider agent

**Actual result:**
Response code is 200 although the cx_warning response header parameter is correctly set