[@typespec/spec-dashboard] Release Spec Dashboard (#5397)

The new pipeline
https://dev.azure.com/azure-sdk/internal/_build?definitionId=7395&_a=summary
has been given access to the storage account through security group. So,
it is not required for any connection string to be in the yml file. This
PR removes this string.

Please review and approve this PR. Thanks

eng/tsp-core/pipelines/dashboard-deploy.yml

@@ -5,9 +5,6 @@ trigger:
       # For patch releases
       - release/*
 
-variables:
-  connectionString: $(AZ_SPEC_DASHBOARD_CONNECTION_STRING)
-
 extends:
   template: /eng/common/pipelines/templates/1es-redirect.yml
   parameters:
@@ -41,5 +38,5 @@ extends:
                   scriptLocation: "inlineScript"
                   inlineScript: |
                     echo "Uploading files to Azure Blob Storage..."
-                    az storage blob upload-batch --source packages/spec-dashboard/dist/ --destination '$web' --overwrite --connection-string "$AZURE_STORAGE_CONNECTION_STRING"
+                    az storage blob upload-batch --source packages/spec-dashboard/dist/ --destination '$web' --overwrite
                   displayName: "Upload files to Azure Blob Storage"