Clustering GeometryCollections in sleep state forces them to awake

The sleep state will be overwritten in ClusterUnionManager::UpdateAllClusterUnionProperties.

Clustering using AClusterUnionActor results the same behavior as well.

1. Place two geometry collections on the level
2. Select the actors in the geometry collection
3. Set the StartAwake property to false in the Details pane
4. Start PIE
5. Ensure that the geometry collections are asleep and stationary
6. End PIE
7. Select the actors again
8. Set ClusterGroupIndex to 1
9. Start PIE

Result:

Clustered rigid body awakens and falls