manifest: Update webkitgtk configure options
manifest: Update webkitgtk configure options

Attempt to disable maintainer mode.

chergert/gnome-continuous,GNOME/gnome-ostree,vrutkovs/vrutkovs.github.io,GNOME/gnome-ostree,vrutkovs/vrutkovs.github.io,vrutkovs/vrutkovs.github.io,GNOME/gnome-ostree,chergert/gnome-continuous,chergert/gnome-continuous