Move scroller/graphicsview example into tests/manual

The example seems incomplete, is undocumented (and unused in shippets,
in spite of tags being present), and generally full of comments that
give the impression that this is for manual testing rather than showing
best practices.

Change-Id: Ie615420e493cc6bb461c5d9ff8d4ae82bb3591db
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>
(cherry picked from commit b908c5cf28923a3ae2d9262361a9810bc57cc9c7)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

examples/widgets/CMakeLists.txt

@@ -17,7 +17,6 @@ add_subdirectory(itemviews)
 add_subdirectory(layouts)
 add_subdirectory(painting)
 add_subdirectory(richtext)
-add_subdirectory(scroller)
 add_subdirectory(tools)
 add_subdirectory(touch)
 add_subdirectory(tutorials)

examples/widgets/widgets.pro

@@ -17,7 +17,6 @@ SUBDIRS       = \
                 mainwindows \
                 painting \
                 richtext \
-                scroller \
                 tools \
                 touch \
                 tutorials \