QmlDesigner: Fix ambiguous ids in plugin testproject

Change-Id: I05b077f52d643703d0714df99968eb05dfd07dc2
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

tests/manual/qml/testprojects/plugins/imports/MyPlugin/MyComponent.qml

@@ -29,10 +29,10 @@ Rectangle {
     width: 60
     height: 60
     color: "green"
-    property alias text: text.text
+    property alias text: textItem.text
 
     Text {
-        id: text
+        id: textItem
         anchors.centerIn: parent
     }
 }

tests/manual/qml/testprojects/plugins/imports/MyPlugin/MyComponent2.qml

@@ -26,7 +26,7 @@
 import QtQuick 2.0
 
 Item {
-    property alias text: text.text
+    property alias text: textItem.text
     property alias color: rect.color
     property alias radius: rect.radius
 
@@ -36,7 +36,7 @@ Item {
         color: "green"
 
         Text {
-            id: text
+            id: textItem
             anchors.centerIn: parent
         }
     }