Confusion around branching being possible for "Attestation" but not "Searchable list"

## Description
The choice of option allows for branching.
- With attestation there is no choice as all options are mandatory, therefore branching should not apply.
- With searchable list, there is a choice like a regular dropdown, therefore branching should apply.

## Steps to reproduce
1. Go to GC Forms
2. Add a page with attestation and searchable list, each with a few options.
3. Add a few pages
4. Go to branching tab
5. Try adding branches based off both types of questions
6. See how it's possible for attestation but not for searchable list

## Details
- **Browser**: Chrome
- **Operating system**: Mac
- **Environment**: Staging
- **Language**: English
- **Viewport**: Desktop

## Expected behaviour
No branching for attestation.
Branching for searchable list.

## Screenshots or videos