QmlDesigner: Fix amok running thread

It looks like the possible import collection function is searching the
home directory. We don't need that for out use case. So we disable it.

Task-number: QDS-14728
Change-Id: Ie09514543497864c0e08fa0581e88a6892cc134d
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>
(cherry picked from commit e1eca653dd)
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

src/plugins/qmldesigner/imagecachecollectors/imagecachecollector.cpp

@@ -86,6 +86,7 @@ void ImageCacheCollector::start(Utils::SmallStringView name,
         "generate image in standard collector");
 
     RewriterView rewriterView{m_externalDependencies, RewriterView::Amend};
+    rewriterView.setPossibleImportsEnabled(false);
     NodeInstanceView nodeInstanceView{m_connectionManager, m_externalDependencies};
     nodeInstanceView.setCaptureImageMinimumAndMaximumSize(captureImageMinimumSize,
                                                           captureImageMaximumSize);