New databaseCommand isn't plumbed into docker environment variables

Is your feature request related to a problem? Please describe.

I was excited to try out the changes from #9879 and #9156, but was a bit disappointed to find that the docker environment variables are not wired up.

As it currently stands, for temporalio/server image there's no DATABASE_COMMAND environment variable or similar, forcing me to pass in a manual config into the server image which is a little awkward for my setup. It works, but it just feels like an oversight

Describe the solution you'd like

The databaseCommand field to be added to config/docker.yaml with an appropriate environment variable like DATABASE_COMMAND

Describe alternatives you've considered
I think this is fairly self-explanatory. The other approach would not be to add it, and require users to fallback to specifying their own config file rather than using environment variables

Additional context
Looks like similar changes were made to the Helm chart here, but in my setup I'm running the docker containers directly (on Azure Container Apps, long story) which would benefit from this approach, so I can connect to my PostgreSQL database using Azure Entra

Start with config/docker.yaml and compare its existing environment-variable mappings with the databaseCommand setting introduced by #9879 and #9156. Wire the setting to DATABASE_COMMAND, then verify that the Temporal server Docker image accepts the variable for PostgreSQL configuration.