feat(keycloak): add support for KC_LOG_LEVEL env variable

KC_LOG_LEVEL is defined in the [official docs](https://www.keycloak.org/server/all-config?q=log-level).

testing/external-keycloak.yml

@@ -32,6 +32,7 @@ services:
       KC_DB_USERNAME: ${KC_DB_USERNAME:-keycloak}
       KC_DB_PASSWORD: ${KC_DB_PASSWORD:-keycloak}
       KC_FEATURES: impersonation
+      KC_LOG_LEVEL: ${KC_LOG_LEVEL:-INFO}
       KC_PROXY_HEADERS: xforwarded
       KC_HTTP_ENABLED: true
       KEYCLOAK_ADMIN: ${KEYCLOAK_ADMIN:-kcadmin}