[llvm] ci: Fix `pr-code-format` permissions for private forks (PR #120838)

[Tom Stellard via llvm-commits]

tstellar wrote:

> https://github.com/llvm/llvm-project/blob/e21dc4bd5474d04b8e62d7331362edcc5648d7e5/llvm/utils/git/code-format-helper.py#L133-L136

I the llvm/llvm-project main branch, this code never gets called, because we pass the --write-comment-to-file option.


https://github.com/llvm/llvm-project/pull/120838