Workaround for enabling of kernel v4.4 breaks nsx-t tests

We use WORKSPACE variable for directories consisting fuel-qa, but not for fuel-qa itself (and fuel-qa is loaded as submodule to the folder plugin_test https://github.com/openstack/fuel-plugin-nsx-t/tree/master/plugin_test).
Here is what we get on CI now:

ERROR: Create environment and set up master node
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Traceback (most recent call last):
  File "/home/jenkins/90-venv/local/lib/python2.7/site-packages/proboscis/case.py", line 296, in testng_method_mistake_capture_func
    compatability.capture_type_error(s_func)
  File "/home/jenkins/90-venv/local/lib/python2.7/site-packages/proboscis/compatability/exceptions_2_6.py", line 27, in capture_type_error
    func()
  File "/home/jenkins/90-venv/local/lib/python2.7/site-packages/proboscis/case.py", line 350, in func
    func(test_case.state.get_state())
  File "/home/jenkins/workspace/9.x.nsxt.custom.qa/plugin_test/fuel-qa/fuelweb_test/helpers/decorators.py", line 120, in wrapper
    result = func(*args, **kwargs)
  File "/home/jenkins/workspace/9.x.nsxt.custom.qa/plugin_test/fuel-qa/fuelweb_test/tests/base_test_case.py", line 402, in setup_master
    self.rebuild_bootstrap_image_with_xenial_kernel()
  File "/home/jenkins/workspace/9.x.nsxt.custom.qa/plugin_test/fuel-qa/fuelweb_test/tests/base_test_case.py", line 199, in rebuild_bootstrap_image_with_xenial_kernel
    for script in os.listdir(script_path):
OSError: [Errno 2] No such file or directory: '/home/jenkins/workspace/9.x.nsxt.custom.qa/fuelweb_test/useful_scripts/'

If we change workspace to fuel-qa, then we get:
python: can't open file 'plugin_test/run_tests.py': [Errno 2] No such file or directory