function overrideSettingsForGatherMode(settings, gatherMode) {
  if (gatherMode === 'timespan') {
    if (settings.throttlingMethod === 'simulate') {
      settings.throttlingMethod = 'devtools';
    }
  }
}
Overrides the settings that may not apply to the chosen gather mode.

@param {LH.Config.Settings} settings
@param {LH.Gatherer.GatherMode} gatherMode