Update keycloak image version and env vars

Author: javorszky

tests/data/common/app/keycloak/app.yaml

@@ -30,15 +30,17 @@ spec:
     spec:
       containers:
       - name: keycloak
-        image: quay.io/keycloak/keycloak:26.3
+        image: quay.io/keycloak/keycloak:26.4
         args: ["start-dev"]
         env:
-        - name: KEYCLOAK_ADMIN
+        - name: KC_BOOTSTRAP_ADMIN_USERNAME
           value: "admin"
-        - name: KEYCLOAK_ADMIN_PASSWORD
+        - name: KC_BOOTSTRAP_ADMIN_PASSWORD
           value: "admin"
-        - name: KC_PROXY
-          value: "edge"
+        - name: KC_HOSTNAME_STRICT
+          value: "false"
+        - name: KC_PROXY_HEADERS
+          value: "xforwarded"
         ports:
         - name: http
           containerPort: 8080