test: remove load system certs functionality for s2n_default_tls13_config

tests/fuzz/s2n_certificate_extensions_parse_test.c

@@ -51,9 +51,6 @@ static const uint8_t TLS_VERSIONS[] = {S2N_TLS13};
 
 int s2n_fuzz_init(int *argc, char **argv[])
 {
-    /* Initialize the trust store */
-    POSIX_GUARD_RESULT(s2n_config_testing_defaults_init_tls13_certs());
-    POSIX_GUARD(s2n_enable_tls13_in_test());
     return S2N_SUCCESS;
 }
 
@@ -67,8 +64,12 @@ int s2n_fuzz_test(const uint8_t *buf, size_t len)
     POSIX_GUARD(s2n_stuffer_alloc(&fuzz_stuffer, len));
     POSIX_GUARD(s2n_stuffer_write_bytes(&fuzz_stuffer, buf, len));
 
+    DEFER_CLEANUP(struct s2n_config *config = s2n_config_new(), s2n_config_ptr_free);
+    POSIX_GUARD(s2n_config_set_cipher_preferences(config, "20240503"));
+
     struct s2n_connection *client_conn = s2n_connection_new(S2N_CLIENT);
     POSIX_ENSURE_REF(client_conn);
+    POSIX_GUARD(s2n_connection_set_config(client_conn, config));
 
     /* Pull a byte off the libfuzzer input and use it to set parameters */
     uint8_t randval = 0;

tls/s2n_config.c

@@ -251,12 +251,6 @@ int s2n_config_defaults_init(void)
     return S2N_SUCCESS;
 }
 
-S2N_RESULT s2n_config_testing_defaults_init_tls13_certs(void)
-{
-    RESULT_GUARD_POSIX(s2n_config_load_system_certs(&s2n_default_tls13_config));
-    return S2N_RESULT_OK;
-}
-
 void s2n_wipe_static_configs(void)
 {
     s2n_config_cleanup(&s2n_default_fips_config);

tls/s2n_config.h

@@ -239,7 +239,6 @@ struct s2n_config {
 S2N_CLEANUP_RESULT s2n_config_ptr_free(struct s2n_config **config);
 
 int s2n_config_defaults_init(void);
-S2N_RESULT s2n_config_testing_defaults_init_tls13_certs(void);
 struct s2n_config *s2n_fetch_default_config(void);
 int s2n_config_set_unsafe_for_testing(struct s2n_config *config);