Squash to "selftests: mptcp: join: check re-re-adding ID 0 signal"

Just to align with the previous test (delete and re-add), here we do the
same for "delete re-add signal".

It doesn't seem to be an issue on the Netdev CI for the moment, but
better be safe than sorry. Plus, it doesn't change anything for the
test: the connection will run for longer, but it will be killed when all
operations have been done.

Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>

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

@@ -3762,7 +3762,7 @@ endpoint_tests()
 		# broadcast IP: no packet for this address will be received on ns1
 		pm_nl_add_endpoint $ns1 224.0.0.1 id 2 flags signal
 		pm_nl_add_endpoint $ns1 10.0.1.1 id 42 flags signal
-		{ test_linkfail=4 speed=20 \
+		{ test_linkfail=4 speed=5 \
 			run_tests $ns1 $ns2 10.0.1.1 & } 2>/dev/null
 		local tests_pid=$!