Switch the pages-build-container and pages-cf-build-tasks to use the platform hardened base image

[apburnes]

The current pages-build-container and pages-cf-build-tasks uses the Docker official Ubuntu 22 image and we harden the respective images in our build process. Can we switch the base image for the two components to use the cloud.gov platform's managed hardened Ubuntu image.

Acceptance Criteria

• Evaluate the possibility to switch
• If possible, switch the images to use the platform hardened image