[Maps] Increase limit of features per vector tile

[thomasneirynck]

Describe the feature:

The max-number of features in a vector tile is now capped at the default ES-search-limit (`https://www.elastic.co/guide/en/elasticsearch/reference/current/index-modules.html#index-max-result-window). Consider increasing this, e.g. by using scroll-API.

Describe a specific use case for the feature:

The mvt scaling-type was introduced to reduce the size of the data that is being sent over the wire (Kibana-server->browser) and enable client-side caching by using tiles.

These gains would allow for loading even more data on screen, by packing more documents inside a tile, beyond the current limit. This would increase the number of features on screen from the orders of tens/hundreds of thousands to millions of documents.

[elasticmachine]

Pinging @elastic/kibana-gis (Team:Geo)

[thomasneirynck]

Closing: mvt should be supported natively by ES elastic/elasticsearch#58696, which would be the pathway to grow the number of features inside a tile.