review-page: Apply all deferred property changes
That's a funny one: Boxes has a clever mechanism to avoid changing properties constantly (it can be UI blocking to change some of the properties, for example, the storage disk needs to be resized when the user changes the size on the GtkScale). The mechanism basically adds a timeout for properties to be applied later.
Unfortunately, we can't shrink disks, therefore when it comes to storage size, we don't use the timeout mechanism mentioned above. This way, the properties need to be applied manually when the user is ready-to-create the VM.
When adding the new VM Assistant, I didn't account for that, hence this uggly regression.