Update new test to use let variables to follow our testing best practices

What does this MR do?

This MR is a follow up based on a previous MR discussion.

By making this change we follow our testing best practices.

Finally, not related but I did anyway, just to leave the campground cleaner, I have updated the fabrication of the project resource to use the defined convention.

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content