Chart uses deprecated (out of support) Ubuntu 20.04 images

[yehiyam]

Describe the bug
Some of the images in the helm chart are based on Ubuntu 20.04 which is out of support.
Need to update to supported OS

Environment (please provide the following information):

• GPU Operator Version: v25.3.2

[cdesiniotis]

@yehiyam we have moved most of our images to a distroless base image, so we are no longer using ubuntu20.04.