node.go: Add allow-dedupe-failure flag

This makes it possible to temporarily tolerate npm dedupe failures. npm dedupe can apparently crash due to conflicting package versions; if this then blocks CI, it’s quite difficult to resolve the problem (you effectively have to squash all the fixes into a single change, even if multiple upgrades of unrelated packages are required).

An image built with this flag should still be usable, I believe – it will just be larger than would be ideal. That said, maybe it would also be a valid approach to only use this flag to unblock CI, but to stop deploying new images until npm dedupe works again. We’ll see, I think.

Bug: T329553