Run E2E tests on 8 parallel runners

Author: Janne Rönkkö

.github/workflows/shared-run-e2e.yml

@@ -151,7 +151,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        containers: [1, 2, 3, 4]
+        containers: [1, 2, 3, 4, 5, 6, 7, 8]
     steps:
       - name: Create directory for Docker Compose bundle
         shell: bash