Double check if SubjectResolver, resolve_domain is currently used

[stijndehaes]

This always access the database to do a get on your object, which is expensive, if it's unused let's remove it

[stijn-janssens]

it is not I think, was built for future proofness

[vlieven]

Correct, the RBAC model supports domain-based roles, but they are not implemented anywhere else in de codebase (yet)