fix credentials on system-test (#497)
fix credentials on system-test (#497)


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