Remove *.colorDecorators.enabled language specific settings

[mjbvz]

The language specific color decorator settings (css.colorDecorators.enable, scss.colorDecorators.enable, less.colorDecorators.enable, and json.colorDecorators.enable) have been marked as deprecated for at least 7 months. "editor.colorDecorators" is now the proper setting

We should remove these deprecated settings

[octref]

Note to self: Use "deprecationMessage" to mark deprecated, then remove in Dec.

[octref]

Alright, already deprecated. I'll remove it next month.