[JS] Should we promote breakings to operation level

currently, we will promote breakings to operation level if there's any breakings in some reference model.

breaking message like:
```
Operation xxx has a new signature
```

but the actually diff like: https://github.com/Azure/azure-sdk-for-js/pull/36883#discussion_r2644692893

This breaking message doesn't make sence in reviewing.

No source file, test, or entry point is named in the issue. Start by tracing where breaking changes from reference models are promoted to operation-level messages, then inspect the linked Azure SDK for JS discussion for the expected review output; done means the message accurately reflects the actual diff without misleading operation-level wording.

Written by the indexing model from the issue text.