In e2e tests, read NEPTUNE_E2E_WORKPLACE from a non-secret variable (#197)

Author: gabrys

.github/workflows/tests-e2e.yml

@@ -49,7 +49,7 @@ jobs:
 
       - name: Run tests
         env:
-          NEPTUNE_E2E_WORKSPACE: ${{ secrets.E2E_WORKSPACE }}
+          NEPTUNE_E2E_WORKSPACE: ${{ vars.NEPTUNE_E2E_WORKSPACE }}
           NEPTUNE_E2E_API_TOKEN: ${{ secrets[format('E2E_API_TOKEN{0}', matrix.env_suffix)] }}
           NEPTUNE_HTTP_REQUEST_TIMEOUT_SECONDS: "15"
           NEPTUNE_QUERY_FILES_TIMEOUT: "240"