soletta_stability.py: fix the test setup bug
soletta_stability.py: fix the test setup bug

fix the bug: adjust create folder success and raise assert

Signed-off-by: Lei Yang <884188bc707cc1be54d02b83a73b4695f136ccae@intel.com>

wanghongjuan/meta-iotqa-1,wanghongjuan/meta-iotqa-1,daweiwu/meta-iotqa-1,ostroproject/meta-iotqa,ostroproject/meta-iotqa,wanghongjuan/meta-iotqa-1,wanghongjuan/meta-iotqa-1,daweiwu/meta-iotqa-1,wanghongjuan/meta-iotqa-1,daweiwu/meta-iotqa-1,ostroproject/meta-iotqa,daweiwu/meta-iotqa-1,ostroproject/meta-iotqa,ostroproject/meta-iotqa,daweiwu/meta-iotqa-1