[contrail] incorrect import of ConnectTimeoutError

[Ruslan Khozinov]

Detailed bug description:
 ImportError: cannot import name ConnectTimeoutError has raised because of incorrect import
Steps to reproduce:
 Start test with contrail_bvt testgroup
Expected results:
 Test should be successfully started
Actual result:
 ImportError: cannot import name ConnectTimeoutError
Reproducibility:
 100%
Impact:
 CI, Contrail Plugin Tests

Additional information:
Traceback (most recent call last):
  File "/home/jenkins/workspace/9.1.contrail.5.0.bvt.test.juniper/plugin_test/run_tests.py", line 78, in <module>
    import_tests()
  File "/home/jenkins/workspace/9.1.contrail.5.0.bvt.test.juniper/plugin_test/run_tests.py", line 54, in import_tests
    from tests import test_smoke_bvt # noqa
  File "/home/jenkins/workspace/9.1.contrail.5.0.bvt.test.juniper/plugin_test/tests/test_smoke_bvt.py", line 30, in <module>
    from helpers import vsrx
  File "/home/jenkins/workspace/9.1.contrail.5.0.bvt.test.juniper/plugin_test/helpers/vsrx.py", line 22, in <module>
    from jnpr.junos import ConnectTimeoutError
ImportError: cannot import name ConnectTimeoutError

[Ruslan Khozinov (rkhozinov)]

correct import should be:
from jnpr.junos.exception import ConnectTimeoutError

(related to https://github.com/Juniper/py-junos-eznc/blob/1ca57ae55c2e3909c23ce40ee8368c2f711e3b18/tests/unit/test_device.py)