Add BUILDKITE env var to qaf

Author: JoshMock

.buildkite/run-tests

@@ -19,6 +19,7 @@ run_qaf() {
     -e EC_REGION \
     -e EC_PROJECT_NAME \
     -e VAULT_TOKEN \
+    -e BUILDKITE \
     -v "$(pwd)/cloud.json:/root/.elastic/cloud.json" \
     docker.elastic.co/employees/dolaru/qaf:latest \
     bash -c "$cmd"