[Enhancement] ConnectorRecord and CloudEvents protocol conversion optimization

### Search before asking

- [X] I had searched in the [issues](https://github.com/apache/eventmesh/issues?q=is%3Aissue) and found no similar issues.

### Enhancement Request

Currently, the conversion between ConnectRecord and CloudEvents in the implementation of the connector needs to be standardized. It is necessary to define which fields are extended by the user and which are the attributes needed by the mesh or connector. This requires unified standardized processing and optimization.

### Describe the solution you'd like

Currently, the conversion between ConnectRecord and CloudEvents in the implementation of the connector needs to be standardized. It is necessary to define which fields are extended by the user and which are the attributes needed by the mesh or connector. This requires unified standardized processing and optimization.

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

The issue does not name any files, tests, or entry points. First identify the connector implementation and its ConnectRecord/CloudEvents conversion paths, then clarify the standardized field boundaries and optimization requirements before defining done.

Written by the indexing model from the issue text.