Don't use an interactive rebase when rebasing onto another branch

**Is your feature request related to a problem? Please describe.**
Currently we always interactive rebase when rebasing onto another branch. This is not obvious behaviour and causes surprising behaviour (as we saw in https://github.com/jesseduffield/lazygit/pull/2429).

**Describe the solution you'd like**
We should not pass --interactive when rebasing onto a branch, BUT we should _still_ show the commits that are yet to come in the rebase, because the visual aid is handy.