[SW-2612] Change K8s Base Image for Spark 2.4 to openjdk:8-jdk-slim-buster

[mn-mikke]

openjdk:8-jdk-slim used to be based on the buster (debian apt) repository:

/etc/apt/sources.list:# deb http://snapshot.debian.org/archive/debian/20210621T000000Z buster main
/etc/apt/sources.list:deb http://deb.debian.org/debian buster main
/etc/apt/sources.list:# deb http://snapshot.debian.org/archive/debian-security/20210621T000000Z buster/updates main
/etc/apt/sources.list:deb http://security.debian.org/debian-security buster/updates main
/etc/apt/sources.list:# deb http://snapshot.debian.org/archive/debian/20210621T000000Z buster-updates main
/etc/apt/sources.list:deb http://deb.debian.org/debian buster-updates main

now it's based on the bullseye (debian apt) repository:

/etc/apt/sources.list:# deb http://snapshot.debian.org/archive/debian/20210902T000000Z bullseye main
/etc/apt/sources.list:deb http://deb.debian.org/debian bullseye main
/etc/apt/sources.list:# deb http://snapshot.debian.org/archive/debian-security/20210902T000000Z bullseye-security main
/etc/apt/sources.list:deb http://security.debian.org/debian-security bullseye-security main
/etc/apt/sources.list:# deb http://snapshot.debian.org/archive/debian/20210902T000000Z bullseye-updates main
/etc/apt/sources.list:deb http://deb.debian.org/debian bullseye-updates main

This repository change causes failure of building spark-py docker image for the version 2.4. The newer repo is missing packages for python 2.7.

This PR changes the base image for Spark 2.4 images to openjdk:8-jdk-slim-buster. The change was manually verified on EKS cluster.