Switch sphinxcontrib-docbookrestapi to python-jobs

As the gate-{name}-python34 job-template is in the python-jobs
group, update sphinxcontrib-docbookrestapi to use that group instead
of directly instantiating job templates. This is in preparation of
turning python34 testing on everywhere we currently run python33
jobs, so we can begin to transition.

Change-Id: I0343d50491c4d6566db10165fa502fdb4fb3bff0
Merge "Switch sphinxcontrib-docbookrestapi to python-jobs"