Disconnect watcher for xdgActivationTokenArrived
XdgActivationTokens are loaded async. To acheive a job like pattern we were comparing serials in our slot when one was created.
On wayland this isn't ideal because we're slowly building up an increasingly long list of lambdas being run, but they'll all no-op.
On X11 because lastInputSerial is always 0 we run the slot multiple times for every system tray item each time an item is clicked or an application is launched.
For xembedsniproxy this is especially problematic as we will trigger synthesised input events in our slot.
Patch untested as it means loading an X11 session.
Edited by David Edmundson