test: increase runInAsyncScope() coverage

We don't appear to have any test coverage for passing the `thisArg`
argument to `runInAsyncScope()`. Test coverage stats seem to bear this
out. Add a test for it.

PR-URL: https://github.com/nodejs/node/pull/36624


Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>