The cancellation can be because of a background problem, or because the user received another verification request from the same user. The cancel function does get called, however due to the speed of our dialog handling the state ends up being lost forever. Instead of trying to de-layer dialogs, this just fastforwards the whole dialog to "cancelled" on mount if required.
Fixes https://github.com/vector-im/riot-web/issues/10118
Travis Ralston