selftests: mptcp: connect: avoid double packet traces

When the same netns is used for the listener and the connector, no need
to take exactly the same packet trace twice, one is enough.

This avoids confusions when the traces are the same, and wasting
resources which might not help reproducing an issue.

While at it, avoid long lines and double spaces now that these lines are
no longer aligned.

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-v1-6-863cb04e1b7b@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/mptcp/mptcp_connect.sh

@@ -375,11 +375,15 @@ do_transfer()
 		local capfile="${rndh}-${connector_ns:0:3}-${listener_ns:0:3}-${cl_proto}-${srv_proto}-${connect_addr}-${port}"
 		local capopt="-i any -s 65535 -B 32768 ${capuser}"
 
-		ip netns exec ${listener_ns}  tcpdump ${capopt} -w "${capfile}-listener.pcap"  >> "${capout}" 2>&1 &
+		ip netns exec ${listener_ns} tcpdump ${capopt} \
+			-w "${capfile}-listener.pcap" >> "${capout}" 2>&1 &
 		local cappid_listener=$!
 
-		ip netns exec ${connector_ns} tcpdump ${capopt} -w "${capfile}-connector.pcap" >> "${capout}" 2>&1 &
-		local cappid_connector=$!
+		if [ ${listener_ns} != ${connector_ns} ]; then
+			ip netns exec ${connector_ns} tcpdump ${capopt} \
+				-w "${capfile}-connector.pcap" >> "${capout}" 2>&1 &
+			local cappid_connector=$!
+		fi
 
 		sleep 1
 	fi
@@ -416,7 +420,9 @@ do_transfer()
 	if $capture; then
 		sleep 1
 		kill ${cappid_listener}
-		kill ${cappid_connector}
+		if [ ${listener_ns} != ${connector_ns} ]; then
+			kill ${cappid_connector}
+		fi
 	fi
 
 	mptcp_lib_nstat_get "${listener_ns}"