maven-release-plugin should push less often to git server

mvn release:prepare runs three times git push which is bad:

A single push at the end is enough to bring all commits and tags to the server finally
It consumes more time than essentially necessary
It is risky, because in case the first POM change A-SNAPSHOT -> A is pushed to the server but an error happens (bug in plugin, crash of client, whatever) then a "half prepared" state is on the server (the second POM change A -> B-SNAPSHOT is missing) and you cannot auto-recover from that without manual action (as mvn release:clean does not undo the tag). If there is only one single push at the end, then EVERYTHING, two commits and a tag, is pushed as a single transaction to the server, which is much better!