When one changes containment plugin, the rest of the configuration
options don't apply or in some cases don't work - changing a wallpaper
and containment type will result in the old containment getting updated
only to be immediately destroyed.
Fixing that is quite difficult (I spent a while, but not got anything
tidy).
So instead make an intermediate solution of at least not presenting the
user with broken options.
CCBUG: 355642