Remove some unused jobs
Remove some unused jobs

These jobs are not used in zuul/layout.yaml, remove them:
* hook-poppy-ui-rtfd
* sahara-propose-translation-update-mitaka
* virtualbmc-docs-ubuntu-trusty
* virtualbmc-docs-ubuntu-xenial

Change-Id: I34821ea9bc90c06ad674df74c49648abff38a031

openstack-infra/project-config,Tesora/tesora-project-config,Tesora/tesora-project-config,openstack-infra/project-config