arrow

MINOR: [CI] Disable UCX for now (#36306)



### Rationale for this change

Tests are flaky, I don't have the time to fix them (I attempted a fix but it seems I need to refactor some more fundamental things: https://github.com/apache/arrow/pull/35796).

### What changes are included in this PR?

Disable UCX build

### Are these changes tested?

Yes

### Are there any user-facing changes?

No

Authored-by: David Li <li.davidm96@gmail.com>
Signed-off-by: Sutou Kouhei <kou@clear-code.com>