DS konfiguration should be loaded directly ConfigMap on K8S [DBZ-7954]

Migrated from [DBZ-7954](https://issues.redhat.com/browse/DBZ-7954)

Debezium Server supports configuration loading from config maps and secrets. However currently we construct the configuration application.properties, which is stored in config map as a while (under single application.properties key) and then mounted as a file. Additional configuration can be loaded from config maps/secrets and referenced in this property file (as it is correctly resolved by smallrye config).

This solution is rather cumbersome. What we should do in k8s is

- enable kuberenetes-config and map/secret sources by defaul via ENVVAR
- have the rest of the configuration only in the config map with each configuration property as it's own entry

Start by locating the Debezium Server Kubernetes configuration and the current application.properties ConfigMap mounting flow. Check how Kubernetes config maps and secrets are exposed through environment variables, then verify that each configuration property can be supplied as its own ConfigMap entry and that referenced sources still resolve correctly.

Written by the indexing model from the issue text.