[CI] Fix Linux aarch64 nightly wheel uploads - #1760

Description

The aarch64 nightly saga continues (#1755, #1756, #1757).

In last night's run, aarch64 builds worked just fine on Python 3.10-3.14t.

However, uploads failed because they tried to upload to S3+PyPI, rather than just PyPI. The S3 half fails because the PyTorch org's OIDC trust policy doesn't include pytorch/tensordict (unlike vision/audio/ao etc.). Because these S3 and PyPI steps were bundled, the PyPI step never ran.

This fixes that by borrowing the upload code from the other tensordict-nightly platforms.

Side notes:

• Python 3.15/3.15t builds fail for an unrelated reason (Fix Python 3.15 smoke tests on Windows and Linux test-infra#8357 made 3.15 smoke tests resolve all runtime deps from download.pytorch.org, where pyvers isn't mirrored, I'll chase that separately). Not aarch64 specific, but aarch64 is the only platform that attempts a 3.15/3.15t build (other platforms stop at 3.14), so it's surfacing here. Not immediately critical to fix as 3.15 isn't released yet, but something to fix later.
• The upload runs with !cancelled() specifically because 3.15/3.15t is a WIP - this lets successful builds (3.10-3.14t) still publish.
• No continue-on-error on the new upload job: if uploads break again I'd rather the run go red than silently green.

Fingers crossed...

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