Introduce wmgUseVectorFooterCleanup

Follows-up 41d665f8ef6456457c0b144a89d62408e3d749b9.

The micro design changes can change over time. We shouldn't
mix their experimentation pool with wikis that specifically requested
certain bits of functionality.

Change-Id: I0a59c7194575b6da887c644431065c475e53a716