Remove unneeded empty check pipeline definitions
jobs:
- openstack-doc-build
- tox-py35-on-zuul
-
-- project:
- name: openstack-infra/openstack-zuul-jobs
- check:
- jobs: []
-
-- project:
- name: openstack-infra/openstack-zuul-roles
- check:
- jobs: []
-
-- project:
- name: openstack-infra/zuul
- check:
- jobs: []
