[maps] Unable to pluck style meta from local data for geo_grid vector tiles for any property other then count

[nreese]

regression from #114553

Steps to view problem:

1. Install web logs sample data
2. create new map, add clusters layer, click add
3. change count metric to "max bytes"
4. set grid resolution to "super fine"
5. Click "Data mapping" under under "Fill color" and uncheck "Get min and max from data set". Notice how the coloring styling is no longer displayed in the map.

Issue is in pluckOrdinalStyleMetaFromTileMetaFeatures.

_mvt returns meta tiles with properties like below

pluckOrdinalStyleMetaFromTileMetaFeatures uses this.getMbFieldName() to get the property name. getMbFieldName returns _count for count property and this exists in meta tile properties. getMbFieldName returns {name}.value for fields and these do not exist in meta tile properties. Thus no style meta is getting plucked for fields.

[elasticmachine]

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