Pin pnpm version for FAB and Edge3 UI so bumps keep security overrides (#72390)

These were the only two pnpm directories in the repo without a
`packageManager` field. Without it, Dependabot resolves them with pnpm 11,
which no longer reads `pnpm.overrides` from `package.json`. It therefore
regenerates `pnpm-lock.yaml` with the `overrides:` block missing entirely,
silently dropping the pinned security patches for transitive dependencies and
breaking frozen installs for the pnpm 10 that the asset-compilation hooks use.

The version matches the one already used everywhere else in the repo.