### What problem does this PR solve?

This PR changes Redis to be a statefulset. In some situation when we
Redis pod gets rescheduled to another Node, it gets stuck in pending
state due to the PVC attached to another Kubernetes node.

### Type of change

- [ ] Bug Fix (non-breaking change which fixes an issue)
- [ ] New Feature (non-breaking change which adds functionality)
- [ ] Documentation Update
- [X] Refactoring
- [ ] Performance Improvement
- [ ] Other (please describe):