glance_store uses bare ConfigParser for swift configuration, that
ceased to strip quotes in PY3. That leads to invalid auth parameters
(e.g. 'project_domain_id': '""') and failure to authenticate.
Current CI process does not hit this issue because Swift backend
is not used.
Change-Id: I6d2c129e6747a3c5fcd2da0c88b0a2135775a914
Closes-bug: #1839772