HEEDLS-621 - fix course delegates URL and Staff List return pages

[DanBloxham-sw]

JIRA link

https://softwiretech.atlassian.net/browse/HEEDLS-621

Description

Fixed the Staff List return page issue for the removal confirmation page, but the link to the page is strangely set up and will point to a bad action when the user has no self assessments.
Fixed the course delegates page by modifying the JS to take query in a whitelisted query parameter and preserve any that match.
Have not been able to fix the screen reader issue.

Screenshots

N/A

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Developer checks

(Leave tasks unticked if they haven't been appropriate for your ticket.)

I have:

• Run the formatter and made sure there are no IDE errors.
• Written tests for the changes (accessibility tests, unit tests for controller, data services, services, view models, etc)
• Manually tested my work with and without JavaScript. Full manual testing guidelines can be found here: https://softwiretech.atlassian.net/wiki/spaces/HEE/pages/6703648740/Testing
• Updated/added documentation in Swiki and/or Readme. Links (if any) are below:
  • doc_1_here
• Updated my Jira ticket with information about other parts of the system that were touched as part of the MR and have to be sanity tested to ensure nothing’s broken.
• Scanned over my own MR to ensure everything is as expected.

[GeorgeBlackwell]

Nice work 🚀 Just a minor comment

[AlexJacksonDS]

Looks OK to me, just the other comment to resolve