Remove the long-form of lost-masonry-wrap flexbox because it doesn't make sense

[peterramsing]

Is this a feature request or a bug report?
Depreciation

What is the current behavior?
lost-masonry-wrap-flexbox: flex/no-flex; will set whether a masonry wrap will be flex or not. But it doesn't really make sense and it probably will cause bugs.

1. It doesn't work on its own.
2. Just setting the gutter on lost-masonry-wrap will not actually set the gutter, it will just take the global setting–it requires whether it'll be flex or no-flex in the shorthand.
3. Just use lost-masonry-wrap: flex;, lost-masonry-wrap-flexbox: flex/no-flex; doesn't seem to help here.

What is the desired behavior?
I'd like to put a warning in place that notifies users that this depreciation will be happening in 9.0. And then when 9.0 rolls around, remove it.

What's the motivation or use-case behind changing the behavior?
Code and documentation simplicity.