Enable globally scoped HTTP auth cache

Description

This policy configures a single global per profile cache with HTTP server authentication credentials. If you disable or don't set this policy, the browser uses the default behavior of cross-site auth. This behavior is to scope HTTP server authentication credentials by top-level site. So, if two sites use resources from the same authenticating domain, credentials need to be provided independently in the context of both sites. Cached proxy credentials are reused across sites. If you enable this policy, HTTP auth credentials entered in the context of one site is automatically used in the context of another site. Enabling this policy leaves sites open to some types of cross-site attacks, and allows users to be tracked across sites even without cookies by adding entries to the HTTP auth cache using credentials embedded in URLs. This policy is intended to give enterprises depending on the legacy behavior a chance to update their login procedures and will be removed in the future.