[llvm] [workflow] Don't add a comment when the first run of the formatter passes (PR #86335)

[Tom Stellard via llvm-commits]

tstellar wrote:

This appears to work, but the workflow that adds the comment is now marked as failed since there is no artifact to download.  The fix for this is to either have the code-formatter workflow produce an empty comment file or to have the pr-comment file to return success when there is no artifact.  I'm thinking maybe the 2nd option is better.

https://github.com/llvm/llvm-project/pull/86335