Edits to blackboard asset re-centers the graph

Steps to reproduce:

1. Create a blackboard asset (let's call it "My Blackboard")
   [Assets > Create > Behavior > Blackboard]
2. Create and open a behavior graph (let's call it "My Graph")
   [Assets > Create > Behavior > Behavior Graph]
3. Pan and zoom around so that the start node is not in the center
4. Add "My Blackboard" to the graph blackboard overlay using the plus icon
5. Open "My Blackboard"
6. Add a variable using the plus icon
7. Go back to "My Graph" window

Actual results: The graph contents are re-centered

Expected results: The graph remains the same

Reproducible with versions: 
1.0.12
1.0.6

Not reproducible with versions: 
1.0.5

Tested on (OS): MacOS