Make sphinx builders configurable in LocalBuildDoc

Sphinx builders were hard coded to be html and man in LocalBuildDoc
before. This enables users to config a list of builders in setup.cfg
as a comma seperated list, e.g. html,man,doctest

Change-Id: I3528b208c7e719286fe8816acf65f8efdc5844c6
Clean up integration script

There are several things in the script that are no longer necessary.
Remove them to clean things up so that we can reason about this
script with less stress.

Change-Id: I02863c8ab98d7e403fada2973a0b5807e1b75595
Enable wheel processing in the tests

In advance of enabling wheel processing in pbr overall, enable it
in the integration testing.

Change-Id: Ide460e000c872902590726639d42a5ecac9e4673
Merge "Make sphinx builders configurable in LocalBuildDoc"