auth: Use KeycloakOpenIDConnect class and fixture factory from swh-auth
The KeycloakOpenIDConnect
class and its mocked version have been moved
to the swh-auth
module in order to reuse them across multiple modules.
So remove duplicated code and adapt tests to use the fixture factory
function from swh.auth.pytest_plugin
.
Related to #3150 (closed)
Migrated from D5303 (view on Phabricator)