message: remove utility and markdown CSS exports
diff: -import React from 'react'
  import {injectGlobal} from 'emotion'
  import {withSystemProps, TYPOGRAPHY} from './system-props'
  // eslint-disable-next-line no-unused
  @@ -21,13 +20,3 @@ const BaseStyles = withSystemProps(
  )
  export default BaseStyles
  -
  -export const UtilityCSS = preval`
  - const {renderSource} = require('../lib/render-sass')
  - module.exports = renderSource('@import "primer-utilities/index.scss";')
  -`
  -
  -export const MarkdownCSS = preval`
  - const {renderSource} = require('../lib/render-sass')
  - module.exports = renderSource('@import "primer-markdown/index.scss";')
  -`
  