perf(load-test): remove parallel flag

Author: klarstil

.github/workflows/load-tests.yml

@@ -22,4 +22,4 @@ jobs:
                   K6_CLOUD_PROJECT_ID: ${{ secrets.K6_CLOUD_PROJECT_ID }}
               with:
                   path: tests/load-tests/**.js
-                  parallel: true
+                  parallel: false