tests: Clean up better after iperf tests

The iperf based test commands create a bunch of .bw and .pid files for
each iperf client and server.  The server side .bw files are cleaned
up afterwards, but the pid files are not, and none of the client side
files are cleaned up.  The latter doesn't really matter when the
client is run on ephemeral guests, but sometimes we run it in a
namespace that shares the filesystem with the host.

Clean up all of these files after the tests.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

test/lib/test

@@ -79,7 +79,7 @@ test_iperf3() {
 	pane_wait "${__pane}"
 	pane_parse "${__pane}"
 	pane_run "${__pane}" 'for i in $(seq 0 '${__procs}'); do'	\
-		'rm -f s${i}.bw; done'
+		'rm -f [cs]${i}.bw [cs]${i}.pid; done'
 	pane_status "${__pane}"
 }