ng_update_migrations will still access the global yarn cache on its `ng update` call and there is no way to avoid this that I can see but if no other integration tests access the global yarn cache then that one test can have free reign over it.
PR Close#35877
This commit moves the build-related scripts
(`build-ivy-npm-packages.js`, `build-packages-dist.js` and
`package-builder.js`) to a dedicated directory to keep the `scripts/`
directory cleaner.
It also moves the logic for building the `zone.js` package to a separate
script, `zone-js-builder.js`, to make it re-usable. A subsequent commit
will use it to build the `zone.js` package when building the Ivy Angular
packages as well.
PR Close#35780