Don't show ResourcesModel messages on the Updates page

Currently messages from the ResourcesModel are shown on only two pages: the Home/Featured page, and the Updates page. Showing the messages on the Home/Featured page makes sense so that people see them. Not showing them on the browsing and app pages also makes sense since by this point they would be annoying. Not showing them on the Settings and Installed page makes sense since they're not relevant there.

By that logic, we should avoid showing them on the Updates page too; these messages are annoying and not relevant there.

This fixes an issue whereby the "A distro upgrade is available" message weirdly shows up on the Updates page while you're already in the middle of applying that upgrade, which is awkward and confusing.

BUG: 469157 FIXED-IN: 6.0