system-tests: Verbose cleanup of ports and namespaces.

Removal of ports and network namespaces can take a significant amount
of time, and it is not clear if the test is stuck or actually doing
something during that time.  Add some logging to cleanup commands
to see what is going on.

Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

tests/system-common-macros.at

@@ -2,10 +2,7 @@
 #
 # Delete namespaces from the running OS
 m4_define([DEL_NAMESPACES],
-   [m4_foreach([ns], [$@],
-               [ip netns del ns
-])
-   ]
+   [m4_foreach([ns], [$@], [echo removing namespace ns; ip netns del ns])]
 )
 
 # ADD_NAMESPACES(ns [, ns ... ])
@@ -72,7 +69,7 @@ m4_define([ADD_INT],
 #
 m4_define([ADD_VETH],
     [ AT_CHECK([ip link add $1 type veth peer name ovs-$1 || return 77])
-      on_exit 'ip link del ovs-$1'
+      on_exit 'echo removing interface ovs-$1; ip link del ovs-$1'
       CONFIGURE_VETH_OFFLOADS([$1])
       AT_CHECK([ip link set $1 netns $2])
       AT_CHECK([ip link set dev ovs-$1 up])