Modify baremetal_basic_ops test

Did few fixs for scenario baremetal_basic_ops test:
* removed redundant method that already exist in base class
* removed redundant ssh connection
* added additional timestamp verifications:
test checks only if file exists, but doesn't check size or data inside
* fixed conditions:
"if None > 0" doesn't work in python3

Change-Id: I16dfb807ddffa1e0987ff0e4baa2e6353523fc34
1 file changed