[PartTest] Fix testeRectSelectionStartingOnLinks() by hiding info messages

The info message bubble that shows up in the okular window in testeRectSelectionStartingOnLinks()
interfereswith the mosue selection making the test fail on HiDPI monitors
with resolution 3840x2160; hiding the info message lets the unit test pass.

autotests/parttest.cpp

@@ -761,8 +761,8 @@ void PartTest::testeRectSelectionStartingOnLinks()
     QVariantList dummyArgs;
     Okular::Part part(nullptr, nullptr, dummyArgs);
     QVERIFY(openDocument(&part, QStringLiteral(KDESRCDIR "data/pdf_with_links.pdf")));
-    // resize window to avoid problem with selection areas
-    part.widget()->resize(800, 600);
+    // hide info messages as they interfere with selection area
+    Okular::Settings::self()->setShowOSD(false);;
     part.widget()->show();
     QVERIFY(QTest::qWaitForWindowExposed(part.widget()));