gh-124928: Emscripten node support: Clean up old node <= 16 flags

[hoodmane]

These flags are only needed for node <= 16. Node 16 has been end of life since
October of 2023.

• Issue: Emscripten node support: Clean up old node <= 16 flags #124928

[corona10]

Hmm, can we add some assertion to check that user is using Node > 16?

[hoodmane]

Yeah that makes sense I will do that.

[hoodmane]

Okay now it prints the following complaint to standard error and exits with code 1 on old node versions.

Node version must be >= 18, got version v16.20.2

[corona10]

Please also add NEWS.d that now CPython requires Node >= 18 for Emscripten build :)

[bedevere-app]

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

[willingc]

Thanks @hoodmane for cleaning up the old node stuff. Much appreciated.

[freakboy3742]

Code changes look good; as noted elsewhere, a news entry is definitely required (the devguide has details on how to generate one).

I'll also hold off merging until python/steering-council#256 is resolved.

[bedevere-app]

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

And if you don't make the requested changes, you will be poked with soft cushions!