Deleting unnecessary maps in the config

[End-rey]

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

I'm always frustrated when there are fields in the config that are difficult to validate, particularly in the form of a map.
In the node config, there are fields:

• node.attribute_*
• storage.shard.*

Describe the solution you'd like

Make these fields lists.

Describe alternatives you've considered

Leave everything as it is, but then complex validation will remain and it will not be easy to reuse the config.

Additional context

Refs #2981 (comment).
After this, we can use viper.UnmarshalExact for validation and reuse the config in the code.