[REF] survey: on survey.survey, rename some fields to ease understanding

PURPOSE

As new features are about to land in survey, notably live interactions [1]
and new survey building [2] performing a pre cleaning is necessary. In this
PR we clean survey models by: removing unnecessary fields, cleaning some code
and finally renaming models.

SPECIFICATIONS: RENAME THANKS_YOU_MESSAGE ON SURVEY.SURVEY

On survey.survey, rename thanks_you_message to description_done

In this commit we rename thanks_you_message field. Indeed for certifications
or recruitment form, "thank you" is not really the unique content you
would get in a post-survey message. We therefore rename it to description_done
to better indicate its use.

SPECIFICATIONS: RENAME CERTIFICATE ON SURVEY.SURVEY

On survey.survey, rename certificate field to certification

All certification related fields on survey model begin with certification_ .
Only the boolean one telling if a survey is a certification or not is called
certificate. In order to ease grep and ordering it is renamed to certification.

SPECIFICATIONS: RENAME PASSING_SCORE ON SURVEY.SURVEY

on survey.survey, rename passing_score field to scoring_success_min

``passing_score`` field name is not really the best name we could find.
Renaming the field using a ``scoring_`` prefix allow to know this field
is linked to the scoring mechanism.

LINKS

[0] Related to Task ID 2061901 (survey models cleaning and preparation)
[1] Task ID 1972640 (live interactions)
[2] Task ID 2119587 (new frontend for building surveys)

PR #40765