Cloned scene agent shares graph instance due to SceneProcessor Pre-initialization

Steps to reproduce:

1. Create a new BehaviorGraph and open it
2. Disable the OnStart Repeat 
3. Connect a LogMessage and SetVariableValue to the OnStart node
4. Assign a BlackboardVariable<String> to both node with a default value "Hello World"
5. SetVariableValue node set the string to "Invalid"
6. Attach the Graph to a GameObject in the scene
7. Create a script with the provided code and attach it to a GameObject in the scene, then assign to it the agent Gao as Prefab
8. Enter playmode and press space several times

Actual results: 

• Hello World
• Invalid
• Invalid
• ...

Expected results: 

• Hello World
• Hello World
• ...

Reproducible with versions: 1.0.12, 1.0.7

Code:

public class CloneAgent : MonoBehaviour
{
    [SerializeField]
    private GameObject m_Prefab;
    private GameObject m_Instance;

    private void Awake() => m_Prefab.SetActive(false);

    private void Update()
    {
        if (Input.GetKeyDown(KeyCode.Space))
        {
            Clone();
        }
    }

    private void Clone()
    {
        if (m_Instance != null)
        {
            Destroy(m_Instance);
        }

        m_Instance = Instantiate(m_Prefab);
        m_Instance.SetActive(true);
    }
}