The "cm" GameObject is not removed when upgrading a component to Cinemachine 3

Reproduction steps:
1. Open the “IN-70525_repro_project.zip” Project
2. Open the “SampleScene”
3. In the Hierarchy window, open the “Room” GameObject in Prefab mode
4. Select the “VirtualCamera” GameObject
5. In the Inspector window, open the Cinemachine Upgrader and upgrade the component
6. Observe the Hierarchy window

Expected result: the “cm” GameObject gets removed
Actual result: the “cm” GameObject does not get removed

Reproducible with: 3.0.1, 3.1.0 (2022.3.26f1, 2023.2.20f1, 6000.0.0b16)
Couldn’t test with: 2021.3.36f1 (Cinemachine 3 is not available)

Reproducible on: Windows 11
Not reproducible on: No other environment tested

Note:

• Not reproducible in an empty project