Backported commits hide attribution

[ignasi35]

When mergify creates a backport PR (for example) where the original commits have "Co-Authors", the co-author information is lost.

See this PR where there are 4 commits backported from this other PR. Note how the first two commits are the result of several people but that information seems to be lost on the cherrypicked commit.

I suspect the problem is the original commit message is modified to append (cherry picked from commit 5855906). GitHub expects the Co-Authored-By lines at the end of the commit message, so the modified commit message shadows that info.