Move bash8 to run under pep8 tox env

To make sure we catch bash8 violations, run under the check and
gate pep8 checks. We do not run a distinct bash8 job for Keystone.

Change-Id: I07ddf419483ad4ab73d9f34568fca0df3d9ca248
Merge "Move bash8 to run under pep8 tox env"