[BUG] auto_scroll should default to false

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Current Behavior

This is common behaviour of most terminal emulators, and it's also default for nvim's terminal. toggleterm should not change that, it's confusing, and time consuming to change, and this is not toggleterm's main feature. It's a bug, I had to go on forums asking people how to change it and it took a great while to discover that it's toggleterm messing with this.

### Expected Behavior

standard scrollback behavior, ie. auto_scroll = false

### Steps To Reproduce

1. install toggleterm
2. watch it mess with the scrollback behaviour
3. be in the dark for few days, as this is not standard, and you haven't ordered this scrollback behaviour change

### Environment

```Markdown
- OS:
- neovim version:
- Shell:
```

### Anything else?

_No response_