Fix manuals translation jobs

Currently the periodic job manuals-propose-translation-update runs
three times on the same repository instead of running once each for
api-site, openstack-manuals and operations-guide.

Also, manuals-upstream-translation-update does not handle the api-site
repo.

* Change the scripts so that they handle all three repositories.
* Update the jenkins configuration to call the scripts with repository name
  as parameter. This needs new job-templates.
* Create a job-group
* Use job-group for each repository.
* Adjust Zuul for new jobs using a template.
* Update manual jobs in zuul to check for just "master" as branch
  instead of using a regex.

Change-Id: I755730ea43ad05a373704ab2fb7e5b55f1c8aeee
Closes-Bug: #1291844
Merge "Fix manuals translation jobs"