fix(dashboards): Bind state setter (#75076)

I forgot that when you pass along functions like this, you need to call
`.bind(this)`, because `this` changes depending on the callsite.

static/app/views/dashboards/detail.tsx

@@ -733,7 +733,7 @@ class DashboardDetail extends Component<Props, State> {
               splitDecision,
               dashboard,
               modifiedDashboard,
-              stateSetter: this.setState,
+              stateSetter: this.setState.bind(this),
               onDashboardUpdate,
             });
           },