Lighthouse desktop test throttled to 3g

When a lighthouse test is enabled for a desktop viewport, the test is throttled to a 3g connection and the CPU appears to be throttled as well. WPT should use the same out of the box settings as lighthouse and use the following settings:

  rttMs: 40,
  throughputKbps: 10 * 1024,
  cpuSlowdownMultiplier: 1,

See: https://github.com/GoogleChrome/lighthouse/blob/8ed55613d41e47e44d2be032e671571177aa5c53/lighthouse-core/config/lr-desktop-config.js#L17-L19