[GHA] remove newlines from COMMIT_MESSAGES to avoid batch annoyance (#80385)
Is a remediation for a problem pointed out by @bdhirsh
See https://github.com/pytorch/pytorch/pull/80043#issuecomment-1167796028
Test plan:
I have added multiple commits here with some spicy batch special characters. This should NOT ruin windows tests.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/80385
Approved by: https://github.com/seemethere
