[Satellite 6] Even after applying all erratas, webUI still shows that some errata needs to be applied.

Issue

• On Red Hat Satellite 6, even after applying all erratas, webUI still shows that some errata needs to be applied.
• Before Red Hat Satellite 6.2.5, webUI shows only applicable errata, and does not handle installable errata at all.
• Some users may only care about installable errata, and it may be useful to query based on installable errata status.
• Errata Status shows Security Errata Applicable even after installing all available errata in the content view.