QWaylandTabletSeatV2: Do not leak tablet information

Clean up after the information we allocated, this way address sanitizer
doesn't complain about it leaking.

Change-Id: Ib7ade93d6585b8c6be6a71d0497801d9cfe75d2f
Reviewed-by: David Edmundson <davidedmundson@kde.org>

src/plugins/platforms/wayland/qwaylandtabletv2.cpp

@@ -38,6 +38,9 @@ QWaylandTabletSeatV2::~QWaylandTabletSeatV2()
         tool->destroy();
     for (auto *pad : m_pads)
         pad->destroy();
+    qDeleteAll(m_tablets);
+    qDeleteAll(m_tools);
+    qDeleteAll(m_pads);
     destroy();
 }