The `test_win` job is occasionally failing where a super old NodeJS
version is used even though we installed a proper one with `nvm`.

It's unclear how the CircleCI windows VMs differ here, it's coming
up rarely and is hard to reproduce when SSH-ing into VMs. Our best
guess is that the existing NodeJS version from the container/image is
super old and somehow takes precedence over the NVM-managed NodeJS
version. This could happen due to bad ordering in the `$PATH`
environment variable, or NVM not properly being wired up there.

We attempt to fix this by always setting `$PATH` to the NVM symlink
directory manually- with highest priority.

PR Close #48326