Steps to reproduce:
1. Open attached project
2. Open scene test.unity
3. Play the scene
- Note the Inertia Tensor values in the top left corner
4. Remove the Collider component from the Cube gameobject using the Inspector
- Note the Inertia Tensor values do not change
- The values do change if the Collider size is modified through the inspector

Expected: After the collider is removed the Inertia Tensor values are reset automatically
Actual: Removing the collider leaves the old Inertia Tensor values

Reproduced on: 2019.3.0a4, 2017.3.0a2, 2017.2.0b5, 2017.1.0p3, 5.6.3f1