Hide outline rectangle around views (#8507)

* Closes #8494

Removes the highlighted rectangle around views that are hovered or
selected.
Why? Because we already have the tab title for this.

Keeps it for containers, because they have no tab title.



https://github.com/user-attachments/assets/bb407161-f3a8-4c66-bbd9-816f8dd28561

Author: emilk

crates/viewer/re_viewport/src/viewport_ui.rs

@@ -165,6 +165,13 @@ impl ViewportUi {
                         continue;
                     };
 
+                    if matches!(contents, Contents::View(_))
+                        && !should_display_drop_destination_frame
+                    {
+                        // We already light up the view tab title; that is enough
+                        continue;
+                    }
+
                     // We want the rectangle to be on top of everything in the viewport,
                     // including stuff in "zoom-pan areas", like we use in the graph view.
                     let top_layer_id =