TD-191 prevent user adding themself as a supervised member of staff

[OluwatobiAwe]

JIRA link

TD-191

Description

Prevent supervisor adding self to staff list

Screenshots

---

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 (see info on Text Editor settings to avoid whitespace changes)
• 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
• Tested any Views or partials created or changed with Wave Chrome plugin and addressed any valid accessibility issues
• Updated/added documentation in Confluence and/or GitHub Readme. List of documentation links added/changed:
  • 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 and it looks right in the browser