Clone WordPress repo into a tmp/vendor folder

I noticed that the WordPress repo is cloned into the root of the project. I was not expecting this type of behavior, and I don't think it is common across other tools either.

Is there a reason why it is being cloned into a root instead of the `./vendor` folder?

The issue names no files or tests. Locate the entry point that clones WordPress and inspect how PHPUnit setup finds that checkout; verify the destination is ./vendor and that the existing test setup still works.

Written by the indexing model from the issue text.