test/pipes: don't use the shell_job option

It's required to execute the test in Jenkins.
We need to stop using a current terminal. For that we need to
* create a new session
* redirect stdout and stderr in a file.
* close stdin

Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>