LU-10973 lutf: use configured tmp directory for tar

LU-10973 lutf: use configured tmp directory for tar

After the LUTF run is done all the test results on all
the agent nodes need to be tarred, in order to make them
available for review later on. Don't assume the lutf tmp
files are in /tmp/lutf. Use the tmp-dir directory configured
in the lutf configuration.

Add the master only once to the agent list.

Pass PYTHOPATH to agent.

Test-Parameters: trivial
Signed-off-by: Amir Shehata <ashehata@whamcloud.com>
Change-Id: Ic3effcb53f7d27bf31b6adfd8a22900767ff9524
Reviewed-on: https://review.whamcloud.com/44843
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>