Remove excess unification when comparing RelationAtoms (#5627)
Remove excess unification when comparing RelationAtoms (#5627)

## What is the goal of this PR?

We remove an accidentally introduced extra unification step when comparing RelationAtoms introduced in one of the previous PRs.
## What are the changes implemented in this PR?

Make sure we call the equivalence method not calculating the unifier when comparing RelationAtoms.
graknlabs/grakn,lolski/grakn,lolski/grakn,lolski/grakn,lolski/grakn,graknlabs/grakn,graknlabs/grakn,graknlabs/grakn