chore(deps): remove no longer used `v2/yarn.lock`

[agilgur5]

Motivation

• v2's deps were merged with v1 in #153
  • the package.json was removed there, but looks like the yarn.lock was left in

Noticed this in https://github.com/argoproj/argo-ui/pull/432#issuecomment-1879816619

Modifications

• remove v2/yarn.lock

Verification

It has no matching package.json, so it is unused/unuseable.