bitnami/redis images does not support ARM based platforms

Pulling the bitnami/redis image yields the following error:
```
docker pull mcr.microsoft.com/oss/bitnami/redis:6.0.8
6.0.8: Pulling from oss/bitnami/redis
no matching manifest for linux/arm64/v8 in the manifest list entries
```

The bitnami/redis image seems to not support ARM. This repo is used for the [kubernetes tutorial](https://docs.microsoft.com/en-us/azure/aks/tutorial-kubernetes-prepare-app) giving people an extra step they have to fix following the tutorial. For some this might be obvious for others this might be a blocker.

Possible solutions:
- switch to the [official redis images from dockerhub](https://hub.docker.com/_/redis)
- push a copy of the official images to mcr.microsoft.com and use that for the tutorial.

Inspect the repository for the Docker image references used by the Azure voting app and compare the proposed Bitnami and official Redis images. Verify the selected image can be pulled for ARM-based platforms and that the Kubernetes tutorial workflow works without an extra image workaround.

Written by the indexing model from the issue text.