[FW][FIX] survey: missing questions without section in survey

[fw-bot]

Since commit dba4783, a survey can have questions with no section
associated, which means 'page_ids' field will be empty.

This prevents to display some questions of a survey, as we are
still expecting a structure page/questions. To solve it, we first
append questions with no sections, then all other questions.

Description of the issue/feature this PR addresses:
opw-2089932

Current behavior before PR:

Desired behavior after PR is merged:

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Forward-Port-Of: #39015

[fw-bot]

Ping @alt-odoo, @rim-odoo
Cherrypicking b8dca55 of source #39015 failed

stderr:

error: could not apply b8dca55535e... [FIX] survey: missing questions without section in survey
hint: after resolving the conflicts, mark the corrected paths
hint: with 'git add <paths>' or 'git rm <paths>'
hint: and commit the result with 'git commit'
Recorded preimage for 'addons/survey/models/survey_survey.py'

Either perform the forward-port manually (and push to this branch, proceeding as usual) or close this PR (maybe?).

In the former case, you may want to edit this PR message as well.

[alt-odoo]

@rim-odoo

Conflict of this forward PR is solved, but manual restart is needed.
Can you merge it please?

[rim-odoo]

@robodoo r+

C'est la chenille qui redémarre @alt-odoo

[robodoo]

Merged at 149657c, thanks!