test/wpackettest.c: remove ubogus cleanup() in test_WPACKET_quic_vlint_random()

test/wpackettest.c: remove ubogus cleanup() in test_WPACKET_quic_vlint_random()

In the beginning of the iteration, pkt is not initialised yet, so there is
no need to clean it up on RAND_bytes() failure.  Replace "return cleanup(&pkt)"
with plain "return 0"'

Fixes: 416d0a638c16 "QUIC wire format support"
Resolves: https://scan5.scan.coverity.com/#/project-view/65248/10222?selectedIssue=1665422
References: https://github.com/openssl/project/issues/1432
Signed-off-by: Eugene Syromiatnikov <esyr@openssl.org>
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Neil Horman <nhorman@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/28546)