`npm publish packages/libdatadog` never published that directory. npm
parses a bare `foo/bar` argument as a GitHub owner/repo shorthand, so the
release job tried to clone it and failed:

  npm error command git --no-replace-objects ls-remote
    ssh://git@github.com/packages/libdatadog.git
  npm error git@github.com: Permission denied (publickey).

The wasm step escaped this only because `packages/libdatadog/wasm` has
three path segments and cannot be shorthand. Pass an explicit `./` prefix
instead.

That failure also stranded 0.19.0 half-published: the wasm package went
out, the other two did not, and re-running the job to finish the release
would fail on the already-published version. Route all three publishes
through scripts/npm-publish.sh, which skips a version already on the
registry, so the job can be re-run to completion after a mid-sequence
failure.

(cherry picked from commit a66b96eb1489f8a7c0e1238e60b76570900028d4)