(as I noted in slack, I'm struggling to test local a-s with Fenix, but I think this looks correct. I might hold off landing it until I can actually test it though?)

STR:

• Have an account in a bad state needing reauth
• Start to sign in to fix the problem, but close the window instead of completing.
• Select "Remove Account"

Observe fxa-state-machine-error: Invalid state transition: Authenticating -> Disconnect in logcat, the account state remains the same.

There is a FxaEvent::CancelOAuthFlow but doesn't seem to be used in practice. Regardless, this change still seems correct.

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