Use GitHub secret to filter in perftests.yml

The GitHub secret PERF_TESTS_FILTER will control which benchmarks are executed in perftests.yml. Using a plain GitHub repo variable did not work for some reason.

Author: ckadluba

.github/workflows/perftests.yml

@@ -15,7 +15,7 @@ jobs:
         shell: pwsh
 
       - name: Run performance tests
-        run: ./RunPerfTests.ps1
+        run: ./RunPerfTests.ps1 -Filter ${{ secrets.PERF_TESTS_FILTER }}
         shell: pwsh
 
       - name: Upload perf test results artifact