COREPACK_ENABLE_AUTO_PIN should default to 0

[benmccann]

I don't want to use corepack. However, this setting means that every single contributor to my project will need to set COREPACK_ENABLE_AUTO_PIN=0 and be careful not to accidentally check in the packageManager field since corepack will automatically add that field to force itself upon any project you use. This is even more annoying since pnpm can't be used without corepack once the packageManager field is present: pnpm/pnpm#8087