Fix invalid translation call

[ahukkanen]

🎩 What? Why?

This fixes an issue with keyword arguments that broke the tests in the Ruby 3 upgrade PR after #8866 was merged.

This fixes that issue and adds some additional cleanup to that template.

📌 Related Issues

• Related to Remove all the private participants from a participatory space #8866, Update ruby to 3.0 #8452

Testing

• Using the ruby 3 branch
• Create a private assembly
• Add private participants to the assembly
• Go to add more private participants to the assembly
• See an error

📋 Checklist

• ❓ CONSIDER adding a unit test if your PR resolves an issue.
• ✔️ DO check open PR's to avoid duplicates.
• ✔️ DO keep pull requests small so they can be easily reviewed.
• ✔️ DO build locally before pushing.
• ✔️ DO make sure tests pass.
• ✔️ DO make sure any new changes are documented in docs/.
• ✔️ DO add and modify seeds if necessary.
• ✔️ DO add CHANGELOG upgrade notes if required.
• ✔️ DO add to GraphQL API if there are new public fields.
• ✔️ DO add link to MetaDecidim if it's a new feature.
• ❌AVOID breaking the continuous integration build.
• ❌AVOID making significant changes to the overall architecture.

[andreslucena]

👍🏽