Disable wheel testing for `powerpc64le-unknown-linux-gnu` (#11229)
## Summary
I need to look into this later, but the test step is failing to install
Python:
https://github.com/astral-sh/uv/actions/runs/13148286589/job/36694160839.
We already disable this for the non-`le` variant, so this seems ok to
revisit.
