This commit aims to achieve the goal of being able to run the test suite
on Windows with `--test-threads 1`, or more notably allowing Wasmtime's
defaults to work better with the main thread on Windows which appears to
have a smaller stack by default than Linux by comparison. In decreasing
the default wasm stack size a test is also update to probe for less
stack to work on Windows' main thread by default, ideally allowing the
full test suite to work with `--test-threads 1` (although this isn't
added to CI as it's not really critical).
Closes#3857
aeaca2062f