moderation: clicking 'unsure' clears everything

Current: clicking the `Unsure` tick box clears all inputs entered by the tutor

Correct: it should not change any inputs by the tutor. That is just an extra label. The tutor's input should remain.

Start by reproducing the moderation form and trace the handler for the `Unsure` tick box. The fix is done when selecting it adds only the extra label and preserves every input entered by the tutor; verify the behavior with the project's existing checks if available.

Written by the indexing model from the issue text.