rt85919-fetch-lost-connection.t failing on MySQL 8.0.24+ due to new error code

[sharris40]

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See https://dev.mysql.com/doc/mysql-errors/8.0/en/server-error-reference.html#error_er_client_interaction_timeout

The test expects error code 2006 or 2013, both of which are generated by the client library. Since 8.0.24, we receive the error code 4031, ER_CLIENT_INTERACTION_TIMEOUT, which is generated by the server. This new code causes the test to fail.