Checklists remove bullets from regular lists in markdown preview

### Expected

I expect to be able to add a checklist to a markdown note that includes other content, such as a list.

### Observed

When I add a checklist to a markdown note containing a regular list, the markdown preview no longer shows the bullets on the list.

### Reproduced

1. Create a new note.
2. Enable markdown on the note.
3. Add a list to the note, for example:
```
- One
- Two
- Three
```
4. View the markdown preview and confirm the list appears with bullets as expected.
5. Add a checklist item to the note, for example:
```
- One
- Two
- Three

- [ ] One
```
6. View the markdown preview and notice the list no longer has bullets.


Make|Model|macOS Version|App Version
-|-|-|-
Apple|Macbook Pro|10.15.4|1.10.0 beta

Reproduce the issue in a new markdown-enabled note using the checklist and regular-list examples from the report, then trace the macOS markdown preview rendering entry point. Done means regular list items still display bullets when a checklist appears in the same note, including the reported macOS and app version context.

Written by the indexing model from the issue text.