test/timing_load_creds.c: Free contents in error handling to avoid memory leak

test/timing_load_creds.c: Free contents in error handling to avoid memory leak

Add a call to OPENSSL_free() in the error handling path to ensure contents is properly freed and prevent a memory leak.

Fixes: 45479dcee1 ("test/timing_load_creds.c: fix coding style and other (mostly minor) issues")
Signed-off-by: JiashengJiang <jiasheng@purdue.edu>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/27570)