Context logging does not work if we don't do it in a way that
oslo.log can pick up the context.
- Use the thread local storage from the base RequestContext class.
- Use the helper method context.get_current() as appropriate
- Update the custom_backend_auth.
- Remove heat/openstack/common/local.py as it is now not used.
Change-Id: I64f6af5090e98579b93a616bc79f4aaa6cd2b2ee
Closes-bug: 1435588