In some browsers, 2FA login was failing with a "request is already
pending" error. This only applied when `experimental_passkeys` was
enabled and on Chrome only. This was due to the fact that the webauthn
API only supports one auth attempt at a time, so the security key call
needs to abort the passkey's conditional UI request before starting.
I am not sure we can test this. We have system specs that simulate
webauthn credentials and they didn't catch this (probably because the
simulation covers the whole flow).