[autotests] Set breeze icon theme name in integration tests

This is an attempt to get some tests failing on the CI due to not
finding icons fixed. See T8082

autotests/integration/kwin_wayland_test.cpp

@@ -48,6 +48,7 @@ WaylandTestApplication::WaylandTestApplication(OperationMode mode, int &argc, ch
     : Application(mode, argc, argv)
 {
     QStandardPaths::setTestModeEnabled(true);
+    QIcon::setThemeName(QStringLiteral("breeze"));
 #ifdef KWIN_BUILD_ACTIVITIES
     setUseKActivities(false);
 #endif