message: Follow up to .attributes -> attributes cleanup work
  Closes
diff: @@ -496,12 +496,6 @@ export class Container extends EventEmitterWithErrorHandling<IContainerEvents> i
  }
  const protocolSummary = this.protocolHandler.captureSummary();
  - // Back compat / staging - to be removed with next server version bump
  - if (protocolSummary.tree.attributes === undefined) {
  - protocolSummary.tree.attributes = protocolSummary.tree[".attributes"];
  - delete protocolSummary.tree[".attributes"];
  - }
  -
  if (!request.headers?.[CreateNewHeader.createNew]) {
  request.headers = {
  ...request.headers,
  