[v20.x] Revert "deps: update undici to 6.13.0"
Refs: https://github.com/nodejs/node/issues/53186 Refs: https://github.com/nodejs/undici/issues/3267 Refs: https://github.com/nodejs/node/pull/53486 Reverts undici to v6.6.2 cc @mcollina
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Refs: https://github.com/nodejs/node/issues/53186 Refs: https://github.com/nodejs/undici/issues/3267 Refs: https://github.com/nodejs/node/pull/53486 Reverts undici to v6.6.2 cc @mcollina