Remove train jobs from the project's CI queues

As stable/train just was switched to EM phase, we don't need to run
it's tests in the neutron-tempest-plugin CI.
Neutron-tempest-plugin is pinned to the 1.5.0 version in the train
jobs and that will be used in e.g. Neutron stable/train since now.

Change-Id: I2b7522e8d7fa9a973b00e59fcf5a0b5116bc5b6c
2 files changed