fix(testing/config): require auth for alternator tests

Ref scylladb/scylla-enterprise#4708

testing/scylla/config/scylla.yaml

@@ -644,6 +644,7 @@ api_ui_dir: /usr/lib/scylla/swagger-ui/dist/
 api_doc_dir: /usr/lib/scylla/api/api-doc/
 alternator_port: 8000
 alternator_write_isolation: only_rmw_uses_lwt
+alternator_enforce_authorization: true
 enable_ipv6_dns_lookup: true
 
 uuid_sstable_identifiers_enabled: false