test/testutil/main.c: move global_init before test_open_streams

test/testutil/main.c: move global_init before test_open_streams

So it is possible to change the allocator implementation,
as it must be before the first malloc call.

Suggested-by: Matt Caswell <matt@openssl.org>
Signed-off-by: Eugene Syromiatnikov <esyr@openssl.org>
Reviewed-by: Saša Nedvědický <sashan@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Neil Horman <nhorman@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/28059)