[dts] [PATCH V2] tests/pvp_multi_paths_vhost_single_core_performance:remove vectorized=0 by default in test case 9 and optimize code

[Tu, Lijuan]

> Remove vectorized=0 by default in test case 9 and use pmd.start_testpmd() to
> replace session.send_expect() to start and quit testpmd.
> 
> Signed-off-by: Ling Wei <weix.ling at intel.com>

Applied, thanks