wayland: Reset Toplevel::surfaceId after surface is created

Xwayland will re-create the wl_surface object if the X11 window is
unmapped and mapped. That, and the fact that the order in which the
WL_SURFACE_ID client message event is received and the wl_surface object
is created is undefined can cause the following bug:

* WL_SURFACE_ID is received
* the old wl_surface object is destroyed, m_surfaceId is reset to 0
* new wl_surface is created but because m_surfaceId is 0, it won't be
  associated with the x11 window

This change ensures that kwin will associate the wl_surface with x11
window by making it not reset cached surface id when the old wl_surface
is destroyed.

However, we cannot leave m_surfaceId as is because wayland aggressively
re-uses object ids so kwin can associate wrong surface with x11 window.

To prevent that, this change also makes Toplevel::setSurface() reset
cached surface id.

CCBUG: 442936
CCBUG: 426069


(cherry picked from commit 52c9dbb4)