test_file_with_not_existing_path_and_not_default_suffix and
test_file_with_not_existing_path have created tempory file which
share same directory tree, when run test code parallel, one might
fail because the other one has cleaned that directory.
This patch replaces constant directory name with random name.
Change-Id: If663f81bd2f09b8d07fb371bd27237044f17ee6f
Closes-Bug: #1526323