GH-46702: [JS] Remove js/ (#46703)

### Rationale for this change

We moved `js/` in apache/arrow to apache/arrow-js.

### What changes are included in this PR?

Remove `js/` in apache/arrow.

### Are these changes tested?

Yes.

### Are there any user-facing changes?

No.
* GitHub Issue: #46702

Authored-by: Sutou Kouhei <[email protected]>
Signed-off-by: Raúl Cumplido <[email protected]>

Author: kou