Add support for REDIS_USER #645
Description
Is your feature request related to a problem?
The backend and the worker currently does not support redis instance set up to have multiple users.
Describe the solution you'd like
Read and use a REDIS_USER or similar environment variable config and use it.
Additional context
The Kubernetes Helm chart has recently added support for supplying a REDIS_USER environment variable (initially intended for initContainers) to backend and worker services.