chore(ci): use dd-sts for system-tests test optimization

Author: nccatoni

.github/workflows/system_tests.yml

@@ -30,9 +30,12 @@ jobs:
     secrets: inherit
     permissions:
       contents: read
+      id-token: write
       packages: write
     with:
       library: python_lambda
       binaries_artifact: binaries
       scenarios_groups: appsec
       skip_empty_scenarios: true
+      push_to_test_optimization: true
+      dd_sts_policy: datadog-lambda-python