Find: Remove "Filtering" placeholder text

Added by mistake in f48a6bb826.

Change-Id: I843c39a1cec3cd25ef1c6e52784f82d1e5ab68cf
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/plugins/coreplugin/find/findtoolwindow.cpp

@@ -65,6 +65,7 @@ FindToolWindow::FindToolWindow(QWidget *parent)
 
     m_searchTerm = new FancyLineEdit(this);
     m_searchTerm->setFiltering(true);
+    m_searchTerm->setPlaceholderText({});
 
     m_searchLabel = new QLabel(this);
     m_searchLabel->setText(Tr::tr("Search f&or:", nullptr));