As an event participant, I want to be informed if the participant questions have been removed when I edit my registration, so that I can have updated information on data retention related to participant data and so that I can make informed decisions about what I do or do not share.
**Explanation of behavior:** When an organizer removes a question, they no longer see the participant data in the organizer side of the user interface. However, from the data retention standpoint, we always aggregate the answers of the participants, even if the organizer has removed a question. When we do the final aggregation (when the event is over), we check if there is any aggregated data associated with questions that were removed. If there is aggregated data for removed questions, we delete this data. We will also not allow organizers to edit their selection of questions if the event has ended. Overall, by doing this, we change the behavior so organizers can still access data that they choose to collect again (if the event is not over), but it will still delete data if they do not choose to collect it again.
**Acceptance Criteria:**
* Given that an organizer has opened registration,
** And a participant has registered for the event,
*** And the organizer then removes participant question,
**** And the participant chooses to edit their registration,
***** The participant should see: "The following questions have been removed by the organizer. You can still change your responses in case the question is re-enabled."
* Documentation of the [[https://www.mediawiki.org/wiki/Extension:CampaignEvents/Api#Get_your_registration_information | "Get your registration information" ]] API endpoint is updated to mention the `removed` property in the response.
**Visual examples (two possibilities/ideas):**
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