[meta] Fix strict type errors in functional tests

Needs work for self review comments. Ended up writing a custom rector rule that did a lot of the sprintf conversions, but it was not perfect.

Converting to a meta as per 🌱 [meta] Fix strict type errors in kernel tests Active

mstrelan → changed the visibility of the branch 3399413-strict-types-functional to hidden.

mstrelan → closed merge request !5255

Add the latest child issue to the Issue Summary

📌 Add declare(strict_types=1) to all Functional tests Fixed landed and all child issues are completed, I think we are done here - thanks!

Automatically closed - issue fixed for 2 weeks with no activity.