Change 2D Detection Sample Experiment start (facebookresearch#821)

Summary:
Pull Request resolved: facebookresearch#821

The sample for a 2D detection experiment needs to specifically be manual, we force this change in the metadata.

Reviewed By: tymmsc

Differential Revision: D81833064

fbshipit-source-id: 0a4617a71a915e1fe3a53bb2eb64737632c03331

Author: JasonKChow

clients/unity/Packages/com.frl.aepsych/.Samples/Client/Scenes/Examples.unity

@@ -443,7 +443,7 @@ MonoBehaviour:
   autoDisableOtherCanvases: 0
   recordToCSV: 0
   recordResponseTime: 1
-  startMode: 1
+  startMode: 2
   client: {fileID: 0}
   strategy: {fileID: 0}
   configGenerator: {fileID: 0}