test: remove stale commented code
test: remove stale commented code

Opened https://github.com/GoogleCloudPlatform/cloud-trace-nodejs/issues/32 to
track lack of tests for authorizedRequestFactory.

keymetrics/vxx,keymetrics/trassingue,googleapis/cloud-trace-nodejs,matthewloring/cloud-trace-nodejs,googleapis/cloud-trace-nodejs,keymetrics/vxx,ofrobots/cloud-trace-nodejs,googleapis/cloud-trace-nodejs,t9nf/cloud-trace-nodejs,matthewloring/cloud-trace-nodejs,googleapis/cloud-trace-nodejs,keymetrics/trassingue,matthewloring/cloud-trace-nodejs,t9nf/cloud-trace-nodejs,ofrobots/cloud-trace-nodejs