fix(keycloak): set hostname in replicas e2e test to prevent CORS 403s

Without an explicit hostname, Keycloak cannot determine the correct
request origin in a multi-replica setup behind a Kubernetes Service,
causing admin API requests to fail with HTTP 403.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: mikkeldamsgaard

charts/keycloak/ci/e2e-values-replicas.yaml

@@ -15,6 +15,8 @@ database:
     secretName: keycloak-db-password
     secretKey: password
 
+hostname: "keycloak-e2e.keycloak-e2e.svc.cluster.local"
+
 cache:
   stack: kubernetes