Fix nightly tests

[tw4l]

Fixes #2459

• Set /data/ as primary storage access_endpoint_url in nightly test chart
• Modify nightly test GH Actions workflow to spawn a separate job per nightly test module using dynamic matrix
• Set configuration not to fail other jobs if one job fails
• Modify failing tests:
  • Add fixture to background job nightly test module so it can run alone
  • Add retry loop to crawlconfig stats nightly test so it's less dependent on timing

GitHub limits each workflow to 256 jobs, so this should continue to be able to scale up for us without issue.

[ikreymer]

Nice work fixing these, and adding parallelization!