[ENHANCEMENT] Distroless images for optimizely agent.

Description

Namaste,

1. Distroless images are small and per our security team's guidance at Google, we're required to use those images for our deployments. To that effect, we're making a feature request to add the ability to build distroless images
   in addition to images built from scratch and Alpine Linux.

2. We'd appreciate the ability to build using podman.

3. And the ability to deploy built container images to the Google Artifact Registry.

For more information about distroless, please see: https://github.com/GoogleContainerTools/distroless.

Benefits

Low attack surface.
High security standards.

Detail

We would like the ability to run:

   make \
     APP_VERSION=$(git rev-parse HEAD) \
     CONTAINERIZER=podman \
     IMAGE_TAG_PREFIX=<GAR-TAG> \
     ci_build_dockerimage_distroless push_image_distroless

Examples

Please see: https://github.com/GoogleContainerTools/distroless

Risks/Downsides

A little more tooling and build complexity.

Start with the Make targets ci_build_dockerimage_distroless and push_image_distroless, comparing them with the existing scratch and Alpine image targets. Check the requested podman containerizer and Google Artifact Registry tag flow, then verify that the documented make command builds and pushes the distroless image successfully.