Why installed yarn in Official Docker Iamges

[ryota-murakami]

I thought npm is only official package manager of Node.js, but yarn is actually installded by default.
What kind of reason of it and pnpm is doesn't work well Docker build context?
Thanks!

[nschonni]

Some similar discussion in #1645 and some of the linked issues there

[ryota-murakami]

@nschonni Thank you!