Resizing loop : lose every missing response

[QRuhier]

Describe the bug

When we resize a loop (adding/deleting an iteration) , the remaining iterations keep there values, except their missing values

• [x] I tested it on the storybook, which leads me to believe that it's a lunatic bug.

To Reproduce

Steps to reproduce the behavior:

1. questionnaire : issue_1045.json
2. page 2 : set 1 person
3. page 3, 4.1, 4.2 : give answer, then missing, then answer (whatever the order, it's just to have both for seing problem)
4. go back to page 2 : change to 2 persons
5. go back to the loop for your 1st person : the answers you gave remain 👍 but missings values have disappeared 👎

It is the same if for example you had 3 iterations then changed to 2 : the missings for the 2 remaining iterations disappear

Expected behavior

When resizing a loop, the remaining iterations should keep their answers, including missing responses

Version where the bug appeared

Observed on 3.1.0, but was already on 2.7

Browser where the bug was tested

• [ ] Chrome
• [x] Firefox
• [ ] Safari
• [ ] Edge
• [ ] Other (please specify): ___

Additional context

Add any other context about the problem here.