[dts] [PATCH V3] tests/pvp_multi_paths_performance:modify dts code sync with testplan and optimize code

[Tu, Lijuan]

> Remove test case 9 vectorized=1 with testplan, default is vectorized=0 and use
> pmd.start_testpmd() to replace session.send_expect() to start testpmd.
> 
> Signed-off-by: Ling Wei <weix.ling at intel.com>

Applied