Release pipeline failed to publish package while csharp emitter is not defined in tspconfig.yaml

[live1206]

There is no csharp emitter defined in https://github.com/Azure/azure-rest-api-specs/blob/main/specification/dnsresolver/resource-manager/Microsoft.Network/DnsResolver/tspconfig.yaml

Release pipeline shows green for SDK generation but failed in "Publish packages Artifacts" step, details can be found in https://dev.azure.com/azure-sdk/internal/internal%20Team/_build/results?buildId=5536518&view=logs&j=83516c17-6666-5250-abde-63983ce72a49&t=0104da19-5500-51c6-f9d6-914496a5c500&l=10

Since csharp emitter is not defined, "Generate SDK" should fail instead with missing csharp emitter.

[live1206]

cc @raych1