pnpm v10 setup added PNPM_HOME (not PNPM_HOME/bin) to PATH and wrote
a pnpm bootstrap shim there. After upgrading to v11, that shim still
points into the old .tools/<version> install, so PATH continues to
resolve `pnpm` to the pre-update version even though the new version
was installed under global/v11.
Detect that layout during self-update, refresh the shims at PNPM_HOME
so the upgrade actually takes effect, and warn the user to run
`pnpm setup` for a clean migration to the v11 PATH layout.
Closes#11464.
Zoltan Kochan
0219ab2484