build(node4): Drop Node 4 builds which has expired

[BYK]

Summary

Thanks for all the fish Node 4, you won't be missed. Fixes #5872.

Test plan

CI builds should pass.

[Daniel15]

This won't work because ./artifacts/yarn-......tar.gz also matches this glob:

+ PACKAGE_TMPDIR=tmp/debian_pkg
++ ./artifacts/yarn-1.6.0.js ./artifacts/yarn-v1.6.0.tar.gz --version
 
error Command "./artifacts/yarn-v1.6.0.tar.gz" not found.

(https://circleci.com/gh/yarnpkg/yarn/14701?utm_campaign=vcs-integration-link&utm_medium=referral&utm_source=github-build-link)

[BYK]

Thanks! Will see what we can do about it.

[arcanis]

Approve but this is a major change, right? We probably should wait until we want to release a v2 before merging it.

[buildsize]

File name	Previous Size	New Size	Change
yarn-[version].noarch.rpm	917.44 KB	891.63 KB	-25.81 KB (3%)
yarn-[version].js	3.97 MB	3.97 MB	-24 bytes (0%)
yarn-legacy-[version].js	4.13 MB	[deleted]
yarn-v[version].tar.gz	922.51 KB	896.86 KB	-25.65 KB (3%)
yarn_[version]all.deb	681.28 KB	664.76 KB	-16.51 KB (2%)

[BYK]

We probably should wait until we want to release a v2 before merging it.

Yeah, I was gonna ask about this. I think this deserves a major version bump :(

[BYK]

Closing as I don't think we'll be releasing another major version of the legacy Yarn at all as Yarn v2 is going along quite well :)