selftests: mptcp: get stats just before timing out

selftests: mptcp: get stats just before timing out

Recently, some debugging happened around a test that was timing out. The
stats were showing connections being closed which was confusing because
the closing state was caused by the timeout stopping the transfer.

To avoid such confusion, the timeout is no longer done per mptcp_connect
process, but separately. In case of timeout, the stats are now printed,
then the apps are killed.

The stats will still be printed after the kill, but that's fine, and
this might even be useful, just in case. Timeout should be exceptional.

Reviewed-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20251114-net-next-mptcp-sft-count-cache-stats-timeout-v1-8-863cb04e1b7b@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>