[TCGC] Fix logic to filter models of Azure.Core

[msyyc]

fix #1408

If there is need to filter models, we shall filter directly instead of clear their usage since:

1. changing usage violate the meaning of usage.
2. language emitter (e.g. Python) may need the real usage of these filtered models

[azure-sdk]

All changed packages have been documented.

• ✅ @azure-tools/typespec-client-generator-core

Show changes

@azure-tools/typespec-client-generator-core - breaking ✏️

Filter Core models directly instead of clear their usage

[azure-sdk]

You can try these changes here

🛝 Playground	🌐 Website	📚 Next docs

[iscai-msft]

We are only changing the value for azure core models, we're basically saying "since everyone has their own models, the usage of these models is technically none". Where does the python sdk fail for azure core models? I believe the issue we were having with usage was needing to know more about models that were used for multipart models

[msyyc]

We are only changing the value for azure core models, we're basically saying "since everyone has their own models, the usage of these models is technically none". Where does the python sdk fail for azure core models? I believe the issue we were having with usage was needing to know more about models that were used for multipart models

For https://github.com/Azure/azure-rest-api-specs/blob/5f24fa2aa4966a7d11892e22c0114f63ee617945/specification/appconfiguration/AppConfiguration/models.tsp#L329, python has to generate this core model since it is referred and azure.core doesn't have similar model to import. If tcgc set the usage with 0, python emitter will filter the core model which is necessary. And as declared in description of this PR, I think clear their usage is not good solution to filter models. If needed, tcgc shall filter it directly.