fix: separate sort and search fields when looking up relationship.

[andershermansen]

Description

Default sort is used as searching field which is causing unexpected behaviour described in #4815 and #5222 This bugfix separates which field is used for sorting and which is used for searching.

Fixes: #4815 #5222

• [X] I have read and understand the CONTRIBUTING.md document in this repository.

Type of change

• [X] Bug fix (non-breaking change which fixes an issue)

Checklist:

• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] Existing test suite passes locally with my changes
• [ ] I have made corresponding changes to the documentation