LU-10973 lnet: LUTF infrastructure updates

LU-10973 lnet: LUTF infrastructure updates

Fix Agent management
Handle python failures properly.
Change default location for temporary files to be in /tmp/lutf

Test-Parameters: trivial
Signed-off-by: Amir Shehata <ashehata@whamcloud.com>
Change-Id: I4e37b6226dfa12de4b7a1f5bfd87f84e91ee1dda
Reviewed-on: https://review.whamcloud.com/44177
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>