[CSV Mapper] Not possible to add Kill chain phase to Uses relationships

[Lhorus6]

Description

In CSV mapper, it is possible to create representations for Kill chain phase. Once these representations exist, they can be used in representations of other entities/relations to add the Kill chain phase to them. However, the "Uses" relationship representation does not find the existing Kill chain phase ("no options").

It's exactly the same problem as this issue, but in a different field : #7419

Environment

6.2.0

Reproducible Steps

Steps to create the smallest reproducible scenario:

1. Create a CSV mapper
2. Create a representation Kill chain phase
3. Create a representation Uses relationship
4. Try to add the Kill chain phase on the Uses relationship
   -> "no options"