plugins/overview, windowview: don't handle keyboard shortcuts on Wayland
The only reason for handling them is that the effect grabs the keyboard, which disables global shortcuts on Xorg. In the Wayland session though, global shortcuts still work while the effects are active, and usually that works fine, as the global shortcuts filter filters out the key press events before they reach the effect. Modifier-only shortcuts though trigger on release, so they don't get filtered out and the shortcut effectively gets triggered twice, once by the effect on press, and once by kglobalacceld on release.