Use new parameter (Azure#49294)

Author: JoshLove-msft

eng/packages/http-client-csharp/ci.yml

@@ -48,6 +48,7 @@ variables:
 extends:
   template: /eng/common/pipelines/templates/archetype-typespec-emitter.yml
   parameters:
+    EmitterPackageJsonPath: /eng/azure-typespec-emitter-package.json
     SparseCheckoutPaths:
       - /sdk/core/Azure.Core/src/Shared
       - /sdk/core/Azure.Core.TestFramework/src