[llvm] Reapply [workflows] Split pr-code-format into two parts to make it more secure (#78215) (PR #80495)

[Aiden Grossman via llvm-commits]

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@@ -31,12 +28,14 @@ jobs:
           separator: ","
           skip_initial_fetch: true
 
-      # We need to make sure that we aren't executing/using any code from the
-      # PR for security reasons as we're using pull_request_target. Checkout
-      # the target branch with the necessary files.
+      # We need to pull the script from the main branch, so that we ensure
+      # we get a version of the script that supports the --write-comment-to-file
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boomanaiden154 wrote:

Nit: I think we should probably reword this to say something about making sure the script is updated rather than specifically mentioning the `--write-comment-to-file` option, which I think would quickly become a dated comment.

https://github.com/llvm/llvm-project/pull/80495