Make SARIF uploads optional but automatic for the main repo (#578)

Author: tonybaloney

.github/workflows/azure-dev-validation.yaml

@@ -27,5 +27,6 @@ jobs:
 
       - name: Upload alerts to Security tab
         uses: github/codeql-action/upload-sarif@v2
+        if: github.repository == 'Azure-Samples/azure-search-openai-demo'
         with:
           sarif_file: ${{ steps.msdo.outputs.sarifFile }}