production: Prepare the environment for the replayers with error reporting

Related to swh/infra/sysadm-environment#4707 (closed)

changed milestone to %Cassandra in production as primary storage [Roadmap - Tooling and infrastructure]

assigned to @vsellier

approved this merge request

added 4 commits

• 111c11aa - 1 commit from branch master
• d055a7c3 - production: Deploy a dedicated redis to store the cassandra replayers errors
• 2981bf33 - production: Declare the namespace to deploy swh using cassandra
• f5319c3b - production: Declare a new swh application using cassandra as a backend

Compare with previous version

merged