selftests: netfilter: nft_queue.sh: reduce test file size for debug build

The sctp selftest is very slow on debug kernels.
Reported-by: Jakub Kicinski <kuba@kernel.org>
Closes: https://lore.kernel.org/netdev/20240826192500.32efa22c@kernel.org/
Fixes: 4e97d521 ("selftests: netfilter: nft_queue.sh: sctp coverage")
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
Link: https://patch.msgid.link/20240827090023.8917-1-fw@strlen.deSigned-off-by: Paolo Abeni <pabeni@redhat.com>

tools/testing/selftests/net/netfilter/nft_queue.sh

@@ -39,7 +39,9 @@ TMPFILE2=$(mktemp)
 TMPFILE3=$(mktemp)
 
 TMPINPUT=$(mktemp)
-dd conv=sparse status=none if=/dev/zero bs=1M count=200 of="$TMPINPUT"
+COUNT=200
+[ "$KSFT_MACHINE_SLOW" = "yes" ] && COUNT=25
+dd conv=sparse status=none if=/dev/zero bs=1M count=$COUNT of="$TMPINPUT"
 
 if ! ip link add veth0 netns "$nsrouter" type veth peer name eth0 netns "$ns1" > /dev/null 2>&1; then
     echo "SKIP: No virtual ethernet pair device support in kernel"