Hypothesis text: If we create the Pretrain deployment environment using existing production MediaWiki container images and begin routing testwiki traffic to it, we will develop confidence that our routing design is sufficiently complete to support the full Pretrain MVP (e.g., all testwiki traffic is reliably served by the Pretrain environment and container).

This is an umbrella task for ServiceOps-owned work to deliver the Pretrain MVP environment and integrate into production traffic routing, such that all testwiki traffic is routed to it. Technical details of the implementation will be expanded upon in subtasks.