Skip flaky subtests of tests/auto/qmltest.

- Skip test_key_click() in events/tst_events.qml.
- Skip test_pixel pixel/tst_pixel.qml.

Task-number: QTBUG-27671
Change-Id: Id78c34244d346910e28a2368f9fe3a41f54b8fb9
Reviewed-by: Janne Anttila <janne.anttila@digia.com>
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>

tests/auto/qmltest/events/tst_events.qml

@@ -73,6 +73,7 @@ Rectangle {
         when: windowShown       // Must have this line for events to work.
 
         function test_key_click() {
+            skip("test_key_click() is unstable, QTBUG-27671")
             keyClick(Qt.Key_Left)
             tryCompare(top, "leftKeyPressed", true, 10000)
             tryCompare(top, "leftKeyReleased", true, 10000)

tests/auto/qmltest/pixel/tst_pixel.qml

@@ -52,6 +52,7 @@ Rectangle {
         when: windowShown
 
         function test_pixel() {
+           skip("test_pixel() is unstable, QTBUG-27671")
            var img = grabImage(rect);
            compare(img.pixel(20, 20), Qt.rgba(255, 0, 0, 255));
            compare(img.red(1,1), 255);