set default transaction rate to coordinator by CI

[sifnoc]

When starting the test, there are queues, each has a rate of throughput for controlling transactions into the coordinator. the organizer is using the first one as default, the queue has a 0.1 tx/s rate.
That would be better to make it flexible at the starting point.

stress-test/src/organizer/queue.ts

Line 104 in ef1d832

const defaultRate = this.config.rates[0]