Consider notifying both committer and author for development branches

We at first designed our Jenkins jobs to notify either the RM for main branches, or the last commiter for development branches.

It was since then raised that it might be interesting to notify both last author and commiter for development branches.

In some case it may have interesting uses, still it means quite a change to our setup. Let see if the need for it raises.

Parent Task: #9614

Original created by @bertagaz on 9615 (Redmine)

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