Cross-communication between Airflow components differs in Airflow2 and Airflow3

### Apache Airflow version 3.1.6 ### If "Other Airflow 3 version" selected, which one? 3.0.1 ### What happened? The following System Tests are not properly parsed by DAG processor in Airflow 3.1.0: - cloud_memorystore_redis - google_analytics_admin - vertex_ai_experiment_service_dag - gcp_vision_annotate_image When adding system tests to Airflow that has not only primitive type objects (for example, object of type Instance, or any Enum value inside some object) as a parameters to the operator, the dag processor does not parse this file at all. Any other error is also not shown on the UI, nor anything at all regarding this DAG. The only exception from the logs of DAG processor that can be caught in the breeze logs (without actually specifying even the system tests that was not parsed): ` dag-processor-manager Traceback (most recent call last): File "/opt/python3.11/lib/python3.11/site-packages/airflow/sdk/execution_time/supervisor.py", line 387, in _fork_main target() File "/opt/python3.11/lib/python3.11/site-packages/airflow/dag_processing/processor.py", line 187, in _parse_file_entrypoint comms_decoder.send(result) File "/opt/python3.11/lib/python3.11/site-packages/airflow/sdk/execution_time/comms.py", line 190, in send frame_bytes = frame.as_bytes() ^^^^^^^^^^^^^^^^ File "/opt/python3.11/lib/python3.11/site-packages/airflow/sdk/execution_time/comms.py", line 148, in as_bytes self.req_encoder.encode_into(self, buffer, 4) File "/opt/python3.11/lib/python3.11/site-packages/airflow/sdk/execution_time/comms.py", line 125, in _msgpack_enc_hook raise NotImplementedError(f"Objects of type {type(obj)} are not supported") NotImplementedError: Objects of type <enum 'Type'> are not supported ` The problem seems to be when passing these "complicated" objects that are also inside 'templated_fields' of the operator. Looks like dag-processor parses the whole system tests and is trying to serialize those variables from templated_fields using Jinja templating to then send this t…