AutoTest: Avoid potential crash

Invalidating the filter model may crash while updating
the source model as it emits a layoutChanged().
Just invalidating the filter works as the sorting of items
is not touched.
Workaround this by explicitly using invalidateFilter()
instead of invalidate().

Task-number: QTBUG-103952
Change-Id: I52abda3936e870bb448c420e98a122edecffda7e
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/autotest/testresultspane.cpp

@@ -228,7 +228,6 @@ void TestResultsPane::addTestResult(const TestResult &result)
     m_atEnd = scrollBar ? scrollBar->value() == scrollBar->maximum() : true;
 
     m_model->addTestResult(result, m_expandCollapse->isChecked());
-    m_filterModel->invalidate();
     setIconBadgeNumber(m_model->resultTypeCount(ResultType::Fail)
                        + m_model->resultTypeCount(ResultType::MessageFatal)
                        + m_model->resultTypeCount(ResultType::UnexpectedPass));