Adapt cudf numba config for numba 0.61 removal

[mroeschke]

Description

closes #17703

Also refactored the old-style class context manager with the new-style @contextlib.contextmanager decorator.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[TomAugspurger]

Looks good thanks.

I looked briefly to see if we could avoid this kind of issue in the future by erroring if we got a deprecation warning from numba, but it looks like that warning was only emitted when the value was set to old_style: https://github.com/numba/numba/blob/53e976f1b0c6683933fa0a93738362914bffc1cd/numba/core/config.py#L93-L96.

[bdice]

Sometimes we choose to manually implement context managers because the overhead of contextlib.contextmanager is pretty high. Is this such a case? The history / blame might tell us.

[mroeschke]

It appears this was added in #13337 without comment about performance, but locally I do see that the decorator version is almost 4x slower than the class version so I'll change this back to the class version.