[BUG] compinit interactive mode overwrites command line

[Andrea Manenti <andrea.manenti@xxxxxxxxx>]

This bug was opened long ago but received no activity. I am reopening a new one hoping to give it more visibility.

## Steps for reproducing

```

% autoload -Uz compinit
% compinit
% zstyle ':completion:*' menu yes select interactive
% ls Do rest-of-command
interactive: Do[]
Documents/  Downloads/

```

Clicking a down arrow or a tab results in

```

% ls Downloads/-command
Documents/  Downloads/
```

## Issue

If a completion is triggered in the middle of a command, what comes next is overwritten. It should be shifted to the right instead.

Important point for reproducing: this only happens if there are *more than one option​*.

## Relevant links:

StackOverflow original question: https://stackoverflow.com/questions/68643931/zsh-s-tab-completion-overwrites-whats-next

zsh Mailing List previous submission: https://www.zsh.org/mla/workers/2021/msg01466.html