Configure Dockerfile for OpenShift restricted security context

[abimichel]

Description

When MALS 2 is deployed to OpenShift, the pod security context and container security context default to 'restricted'.

With Kubernetes restricted security context:

• Pods cannot run as privileged
• Pods cannot mount host directory volumes
• Requires that a pod is run as a user in a pre-allocated range of UIDs
• Requires that a pod is run with a pre-allocated Multi-Category Security (MCS) label

More info: OpenShift Security Context Documentation

Types of changes

Removes use of root user and 1001 user from Dockerfile, as it is suspected that this is causing issues when MALS 2 pods restart (e.g. during Platform upgrades).

Checklist

• [ x] I have read the CONTRIBUTING doc
• I have checked that unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate