test: Remove redundant SSL_CTX_set_max_early_data

Client can only send early data if the PSK allows for it, the
max_early_data_size field can only be configured for the server side.

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5702)