Enable prefab override in entity outliner by default (#15085)

Signed-off-by: Junhao Wang <[email protected]>

AutomatedTesting/Registry/editorpreferences.setreg

@@ -7,7 +7,7 @@
     "O3DE": {
         "Preferences": {
             "Prefabs": {
-                "EnableOutlinerOverrideManagement": false,
+                "EnableOutlinerOverrideManagement": true,
                 "EnableInspectorOverrideManagement": false
             }
         }

Registry/prefab.editor.setreg

@@ -17,5 +17,12 @@
                 }
             }
         }
+    },
+    "O3DE": {
+        "Preferences": {
+            "Prefabs": {
+                "EnableOutlinerOverrideManagement": true
+            }
+        }
     }
-}
+}