Add sub scene creates two nodes for the sub scene and the sub scene under main scene doesn't have the correct icon

Steps to reproduce:

1. Create a project with entity packages
2. Create a subscene by right clicking hierarchy v2

Actual results: two nodes are created for the sub scene and the sub scene under main scene doesn't have the correct icon

Expected results: There should be one subscene node created under main scene with the correct icon applied

Reproducible with versions: 6.3/6.4

Not reproducible with versions: versions prior to 6.3

Can’t test with versions: versions prior to 6.3

Tested on (OS): Mac