test/evp_extra_test.c: Add OPENSSL_free() to avoid memory leak if EVP_PKEY_CTX_set0_r...

test/evp_extra_test.c: Add OPENSSL_free() to avoid memory leak if EVP_PKEY_CTX_set0_rsa_oaep_label() fails

Add OPENSSL_free() to free 'label' if EVP_PKEY_CTX_set0_rsa_oaep_label() fails to avoid memory leak.

Fixes: 21b98da ("rsa: Accept NULL OAEP label for backward compatibility")
Signed-off-by: Jiasheng Jiang <jiashengjiangcool@gmail.com>
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/27835)