Moving Lockout countdown out of error message

re: https://github.com/authgear/authgear-server/issues/3129#issuecomment-1639828138

The lockout countdown should not appear in the error message,
because it looks like the account is still locked after countdown

Start with the discussion linked from issue 3129, especially the referenced comment, then trace where the lockout countdown is placed in the error response. Done means the countdown is no longer shown in the error message and the message does not imply that the account remains locked after the countdown.

Written by the indexing model from the issue text.