test: increase --stack-size to prevent child process failure on ARM

This one is a bit odd as an architecture-specific problem, but on ARM, we get a `Maximum call stack size exceeded` when using require() in the child process. I've bumped it up a bit to avoid the failures so we can test what we are actually after--the stack size isn't actually part of what's being tested.

In both of these tests, the manifestation of the problem is in an `SyntaxError: Unexpected end of input` because the child processes don't end up pushing any stdout so there's nothing to `JSON.parse()`, only stderr with the stack trace.