[maps] clean up feature-state usage

[nreese]

Maplibre feature-state can be used for 2 use cases:

• fast interactions
• data-joins

Maps currently uses both use cases. I propose only using feature state for data-joins, meaning, feature-state will only be used for adding data-joins properties to vector sources.

Reasons:

1. Reduce code complexity and edge cases. Logic required to add values to feature-state and writing expressions to fetch values from feature-state is messy. The complexity exists on many levels. One is that only "paint" properties can use feature-state. Another is that geojson sources can add feature properties to feature-state while vector sources can not add feature properties to feature state.
2. Maps application is not a good candidate for fast interactions use case. The fast interactions use case usually involves updating styling based on user interactions, for example, changing feature styling on hover. Maps does not perform this type of style updates on user interactions.
3. Current implementation of fast interactions use case only supports Geojson sources. Geojson sources are no longer the default (as of 8.0). Maps long term goal is to only use vector tiles for elasticsearch data. Why maintain all this code complexity for a method that we are trying to move away from?

[elasticmachine]

Pinging @elastic/kibana-presentation (Team:Presentation)

[ThomThomson]

Closing this as we will track in our icebox.