qa/workunits/misc/multiple_rsync: put tee output in /tmp

qa/workunits/misc/multiple_rsync: put tee output in /tmp

2013-06-25T10:29:15.811 INFO:teuthology.task.workunit.client.0.err:+ rsync -auv --exclude local/ /usr/ usr.2
2013-06-25T10:29:15.811 INFO:teuthology.task.workunit.client.0.err:+ tee a
2013-06-25T10:29:15.902 INFO:teuthology.task.workunit.client.0.out:sending incremental file list
2013-06-25T10:29:48.738 INFO:teuthology.task.workunit.client.0.out:
2013-06-25T10:29:48.740 INFO:teuthology.task.workunit.client.0.out:sent 1449972 bytes  received 7477 bytes  43505.94 bytes/sec
2013-06-25T10:29:48.740 INFO:teuthology.task.workunit.client.0.out:total size is 3205268241  speedup is 2199.23
2013-06-25T10:29:48.740 INFO:teuthology.task.workunit.client.0.err:+ hexdump -C a
2013-06-25T10:29:48.741 INFO:teuthology.task.workunit.client.0.out:00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
2013-06-25T10:29:48.741 INFO:teuthology.task.workunit.client.0.out:00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 0a 73  |...............s|
2013-06-25T10:29:48.742 INFO:teuthology.task.workunit.client.0.out:00000020  65 6e 74 20 31 34 34 39  39 37 32 20 62 79 74 65  |ent 1449972 byte|
2013-06-25T10:29:48.742 INFO:teuthology.task.workunit.client.0.out:00000030  73 20 20 72 65 63 65 69  76 65 64 20 37 34 37 37  |s  received 7477|
2013-06-25T10:29:48.742 INFO:teuthology.task.workunit.client.0.out:00000040  20 62 79 74 65 73 20 20  34 33 35 30 35 2e 39 34  | bytes  43505.94|
2013-06-25T10:29:48.742 INFO:teuthology.task.workunit.client.0.out:00000050  20 62 79 74 65 73 2f 73  65 63 0a 74 6f 74 61 6c  | bytes/sec.total|
2013-06-25T10:29:48.742 INFO:teuthology.task.workunit.client.0.out:00000060  20 73 69 7a 65 20 69 73  20 33 32 30 35 32 36 38  | size is 3205268|
2013-06-25T10:29:48.742 INFO:teuthology.task.workunit.client.0.out:00000070  32 34 31 20 20 73 70 65  65 64 75 70 20 69 73 20  |241  speedup is |
2013-06-25T10:29:48.743 INFO:teuthology.task.workunit.client.0.out:00000080  32 31 39 39 2e 32 33 0a                           |2199.23.|
2013-06-25T10:29:48.743 INFO:teuthology.task.workunit.client.0.out:00000088

This passes consistently when the output is in /tmp, but fails after a few
iterations when on cephfs+kclient.  Avoid the bug with this test.

See: #5453

Signed-off-by: Sage Weil <sage@inktank.com>