VTN Coordinator test may fail if CPU resource is insufficient.

Sometimes Jenkins job fails on VTN Coordinator test.

https://jenkins.opendaylight.org/vtn/job/vtn-verify/447/

[INFO] [ RUN ] pfc_timer_post.func
[INFO] 2014-06-20 12:57:44.478659: [1658]: FATAL: Failed to assure the resolution

This test expects that the timer callback is called within the specified
period of time. But such tests may fail if the build host is under heavy load.

That is why I decided to disable those tests.