Issue Summary

Runtime in active queries list does not reflect actual runtime.

Steps to Reproduce

1. Go to the list of running queries: https://redash.prod.aws.pbinfra.com/admin/queries/tasks
2. Runtime is never updated from 0s

This differs from my expectations of a constantly incrementing runtime counter.

Technical details:

Browser: Firefox Quantum 57.0.1 (64-bit)
Redash Version: Redash 4.0.0+b3169
How did you install Redash: Deployed as an ECS service