Fix trace processor registration upstream in OpenAI Agents

[tcdent]

The documentation states that we should call addTraceProcessor to register a new processor, but it does not work. Instead, we use this workaround and reference the global trace provider directly.

      // this is the official method for registering a trace processor, but it
      // does not work.
      // addTraceProcessor(processor);

      // instead, we get a reference to the global trace provider and register it directly.
      const { getGlobalTraceProvider } = moduleExports;
      const globalProvider = getGlobalTraceProvider();
      globalProvider.registerProcessor(processor);