Cnh/remove parent concept 11741

[chiatt]

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Description of Change

Prevents the front end from sending a parent concept to be added, when the intent is to remove a relationship to that parent concept.

Issues Solved

Closes #11741

Checklist

• I targeted one of these branches:
  • dev/8.0.x (under development): features, bugfixes not covered below
  • dev/7.6.x (main support): regressions, crashing bugs, security issues, major bugs in new features
  • dev/6.2.x (extended support): major security issues, data loss issues
• I added a changelog in arches/releases
• I submitted a PR to arches-docs (if appropriate)
• Unit tests pass locally with my changes
• I added tests that prove my fix is effective or that my feature works
• My test fails on the target branch

Accessibility Checklist

Developer Guide

Topic	Changed	Retested
Color contrast
Form fields
Headings
Links
Keyboard
Responsive Design
HTML validation
Screen reader

Ticket Background

• Sponsored by:
• Found by: @
• Tested by: @
• Designed by: @

Further comments

[apeters]

lgtm