[book] replace PropagateSubjectRelation*Hook references
PropagateSubjectRelationHook, PropagateSubjectRelationAddHook and
PropagateSubjectRelationDelHook were deprecated by
PropagateRelationHook, PropagateRelationAddHook,
PropagateRelationDelHook respectively in v3.9, and removed in 3.18.
Closes #3420672
