Re-enable CPU test `test/test_python_ops.py -k TestPythonOps` for `uint8` dtype

[tengyifei]

To unblock bumping libtpu pin, we have to disable this test: https://github.com/pytorch/xla/pull/8788/files

This test fails with a LLVM memory allocation error on the CPU.

We should report this bug upstream and re-enable it after a fix is there.

Failed run: https://github.com/pytorch/xla/actions/runs/13668949609/job/38217578967?pr=8788

Error:

E0000 00:00:1741156332.106836   21429 execution_engine.cc:53] LLVM compilation error: Cannot allocate memory
    ./test/run_tests.sh: line 51: 21120 Segmentation fault      (core dumped) python3 "$@"