Force pull container images

**Is your feature request related to a problem? Please describe.**
I am having a container that I can run with different startup commands. (It is a Django project + Celery workers)
The default Docker container configuration is running the Http API.
Then I start a container instance with a different startup command in order to start my celery workers.

As my container name/tag/digest does not change, the worker does not pull the update so my updates are not deployed. I have to stop/delete my container group and recreate a new one.

I can't build container with different tags as my http api is deployed to an app service by a container registry webhook that listen on this tag.

**Describe the solution you'd like**
Add a parameter to azure-cli in order to force pull the new image.

**Describe alternatives you've considered**
Deploy everything with K8S and manage everything by my own