Cleanup not used job aliases

This patch cleans aliases of jobs:

* 'neutron-tempest-plugin-fwaas' which was just an alias for
  the new job 'neutron-tempest-plugin-fwaas-openvswitch'
* 'neutron-tempest-plugin-api' which was just an alias for
  the new job 'neutron-tempest-plugin-ovn'

Those aliases were added temporary as they were used in neutron-lib and
neutron-fwaas repositiories but now both those repositories are updated
and uses new job names so it can be cleaned.

Change-Id: Ib1e233fc467b7de43b8df52b798ce2498b2c7b71
1 file changed