Ensure we're testing the correct state machine

[maddeleine]

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Problem:

When the PR #3747 is merged it will change how the state machine is set. Instead of relying on the conn->actual_protocol_version, now we're relying on a new variable, conn->handshake.state_machine. We have written a lot of tests that set the actual_protocol_version and now the worry is that we might make an assumption that we're testing the TLS13 state machine when we're not.

Solution:

Everywhere in the tests that we set the actual_protocol_version, we should also call s2n_conn_choose_state_machine().