Blacklist failing x/vmware-nsx-tempest-plugin

Tempest sanity job is 100% failing on x/vmware-nsx-tempest-plugin.
Adding this plugin until it is fixed.

- https://zuul.opendev.org/t/openstack/build/45f6c8d3c62d4387a70b7b471ec687c8
- https://zuul.opendev.org/t/openstack/builds?job_name=tempest-tox-plugin-sanity-check

Change-Id: I9c23582e5930156db21b609bc9031ee47e9d6326
1 file changed