Cannot edit user info when polling is open

[Thomas-Upfield]

Description: Convention Organisers should not be able to edit the information of users or switch who the eligible voter is whilst a poll is open.

User Story: As a convention organiser I do not want to undermine the perceived legitimacy of the poll by altering the conditions of the vote midway through.

Acceptance Criteria: Given that I am a CO on the user management page, when a poll is opened, then I can no longer edit any of the details or permissions for alternates or delegates.

[Thomas-Upfield]

More context can be found here: https://input-output-rnd.slack.com/archives/C07SX5Q9RT6/p1731519772718299

[Sital999]

Test reports for above user story are:

• 1-2C-1. Should not be able to switch active voting power between delegate and alternate when polling is open
• 1-2C-2. Should not be able to edit user profile when polling is open