Test that swapping the first app data record with Finished msg works

If the first app data record arrives before the Finished message we should
be able to buffer it and move on to the Finished message.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Hugo Landau <hlandau@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18868)