Utils: Avoid intermediate widgets when using LayoutBuilder

In most cases, the layout constructed in the builder was set
on a widget which in turn was put into a vbox in the actual
widget. This is not necessary, but needs some re-ordering.

Also make sure that using not-yet-parented widgets during
layout construction does not cause visible artifacts.

Change-Id: I75727a571da093d3131ea6fba467c2c646cdb6f1
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/android/androiddeployqtstep.cpp

@@ -517,10 +517,11 @@ QWidget *AndroidDeployQtStep::createConfigWidget()
             AndroidManager::installQASIPackage(target(), packagePath);
     });
 
-    LayoutBuilder builder(widget);
+    Layouting::Form builder;
     builder.addRow(m_uninstallPreviousPackage);
     builder.addRow(resetDefaultDevices);
     builder.addRow(installCustomApkButton);
+    builder.attachTo(widget);
 
     return widget;
 }