emoji verification on login ignores the `m.key.verification.start` sent by the other party

If you

- log in to Element Web
- try to verify the new device with an existing device
- the existing device sends an `m.key.verification.start` message

then the new device will ignore the `m.key.verification.start` message, and when you click the button to start the verification, then it will send its own `m.key.verification.start`, which can cause problems with the glare resolution as defined in https://spec.matrix.org/unstable/client-server-api/#key-verification-framework, since Element Web doesn't notice that there is glare, and both sides may end up waiting indefinitely for the other side to respond.