feature request: dacha2 full publish support

[rvowles]

Feature Request

While Dacha2 is designed to alleviate issues with less stable k8s clusters but storing no initial state and going back to MR for data, it also means that if MR goes down (say for scheduled maintenance on the database) that keys that are not already in the cache will return a 5xx error to Edge, indicating that Dacha is "not ready".

Adding a full-publish would allow the FHOS Operator to take down MR for maintenance without any issues around missing data as long as they maintain stable Dacha2 instances.