Ontology hierarchy reloads when selecting a new entity

[tomi-rli]

Description of the issue

The Ontology Hierarchy reloads whenever an entity that has not been selected before is selected. If an entity that has already been selected is selected again, the hierarchy does not reload.

The expected behavior is that the Ontology Hierarchy is loaded once and does not reload when selecting another entity, regardless of whether the entity has been selected before.

Steps to Reproduce

1. Open the OEO Viewer.
2. Select an entity that has not been selected before.
3. Observe that the Ontology Hierarchy reloads.
4. Select another new entity and observe that the hierarchy reloads again.
5. Select an entity that has already been selected and observe that the hierarchy does not reload.