C419 autofix can remove comment

[Skylion007]

We did a large change of the PyTorch codebase with ruff in pytorch/pytorch#99890 by enabling C419 with autofixes. It mostly worked out of the box, but we did have to add back in one type comment for mypy that got deleted by the autofix: pytorch/pytorch@ad98f63

[charliermarsh]

👍 Thanks. We preserve some comments in the comprehension fixes, but clearly not that one :)

[dhruvmanila]

I can pick this up, wanted to get into CST :)

[dhruvmanila]

Ok, so it seems like we're not copying over the lbracket and rbracket fields from the ListComp node. Now, this is a challenge as we need to convert it into a GeneratorExp which only has the lpar and rpar fields. We'll need to pick the required parts from the Bracket nodes into the Parenthesis nodes.