Now that the builtin rebase is feature-complete, we should use it by
default. Let's keep the legacy scripted version around for the time
being; Once the builtin rebase is well-tested enough, we can remove
`git-legacy-rebase.sh`.
Signed-off-by: Pratik Karki <predatoramigo@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>