Ensure SSL_get_app_data() continues to work even in SSL_free()

Ensure SSL_get_app_data() continues to work even in SSL_free()

During SSL_free() we may get a QUIC TLS callback being called to clean up
any remaining record data. We should ensure that SSL_get_app_data()
continues to work, even in this scenario.

Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/27091)

(cherry picked from commit 2100cf2ee0d377976d28c9e04eefae4e1b5373ea)