Adhere to Kubernetes Pod Security Standards

https://kubernetes.io/docs/concepts/security/pod-security-standards

We'll want to start working towards adhering to at least the `baseline` standard and eventually `restricted`. While most of that will fall onto the https://github.com/kaleido-io/firefly-helm-charts manifests, we do need to do our due diligence within the container images themselves such as setting `USER`, etc.

This issue is meant to track making updates to the FireFly core container image and any others to work towards the initial goal of meeting the `baseline` standard.