Clear out some legacy tox* jobs
Most repositories are now using 'tox-jessie'. Clear out some leftover
tox jobs:
tox-doc
tox-flake8-bin
tox-flake8-bin-jessie
tox-flake8-jessie
tox-py27
tox-py27-jessie
tox-py34
tox-py34-jessie
Keep 'tox-flake8' and 'tox-doc-jessie' which are still being used.
Bug: T126588
Change-Id: I137f0b6d93d4bd129ca721586f5e1f4f5ef679f9