Fix `push-docs` CI for `push` events without code changes. (#9689)
This PR fixes the error found in [this `push-docs` CI run][1] for a
`push` event on `master` branch.
**What happened:**
- `push-docs` failed because it couldn't find the `torch-xla-wheels`
artifact
- The `torch-xla-wheels` artifact wasn't uploaded because its upload and
the dependent build step are coditioned by `inputs.has_code_changes ==
'true'`
**Solution:**
- Build PyTorch and PyTorch/XLA on every `push` event, since that's also
when `push-docs` runs
_Note: `push-docs` job actually needs to install both PyTorch and
PyTorch/XLA, otherwise it can't retrieve the docstrings that we rely on
to build the documentation._
[1]:
https://github.com/pytorch/xla/actions/runs/18698514731/job/53322086395
