s390x support documentation

[jdao-rh]

Description

Here is some notes for things i ran into trying to enable s390x support, mainly documenting missing images needed for the tests cases. Incase someone finds this info useful in the future

Build

Build is successful with command

mvn clean install -fn -Dproductized 

tests

Tests cases fail due to the following missing images :

• confluentinc/cp-kafka:5.4.3
  Can be built from source https://github.com/confluentinc/kafka-images/tree/master/kafka
• infinispan/server:12.1.7.Final
  Downstream Redhat DataGrid image can be used
• vectorized/redpanda v21.5.5
  No Z image viable , fails to compile from sorce on Z
• library/mongo:4.0.10
  Newer version can be used mongo:4.3.2
• prom/prometheus v2.8.0
  Use image https://hub.docker.com/r/ibmcom/prometheus

Implementation ideas

No response