fix(workflowengine): Fix list of checks being a list instead of array…

[nickvergessen]

…<int, …>

Steps

1. Create a flow

2. Reload the page
3. Seems psalm was right and I was wrong 🙈
4. Regression from feat(workflowengine): Add openapi for workflow engine #58278

Expected

Workflow shows

Actual

Error about some() in console

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)

AI (if applicable)

• The content of this PR was partly or fully generated using AI

[szaimen]

🐘