[Maps] [APM] Use Maps in APM instead of custom solution

[thomasneirynck]

APM has a custom map implementation.

1. Consider using the MapsEmbeddable instead for consistent L&F, and reduce duplication of effort. This would be similar to the Maps integration in SIEM and Uptime ([Uptime design] woldmap on monitor details #45561).

2. The APM implementation also has hardcoded dependencies on EMS-resources (

   kibana/x-pack/legacy/plugins/apm/public/components/shared/charts/TransactionCharts/ChoroplethMap/index.tsx

   Lines 45 to 48 in 989489e

   	const MAPBOX_STYLE =
   	'https://tiles.maps.elastic.co/styles/osm-bright-desaturated/style.json';
   	const GEOJSON_SOURCE =
   	'https://vector.maps.elastic.co/files/world_countries_v1.geo.json?elastic_tile_service_tos=agree&my_app_name=ems-landing&my_app_version=7.2.0';

   ). We should migrate to using the EMS-client (https://www.npmjs.com/package/@elastic/ems-client), which will remove this hardcoded dependency, and use the catalog service for service discovery.

3. Instead of migrating the geo maps perhaps we should deprecate aka remove maps from APM since this is being added to CSM in 7.10: [RUM Dashboard] Visitors by region map #77135

[elasticmachine]

Pinging @elastic/apm-ui (Team:apm)

[elasticmachine]

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

[thomasneirynck]

Moving APM to use the ems-client (as a low-effort change) or use the MapsEmbeddable (as preferred change) will be a prerequisite for having in APM work with on on-prem version of EMS.

cc @jensallen @nickpeihl @jsanz

[thomasneirynck]

(1) is the ideal scenario, although (2) will be the smallest change that unblocks Kibana from moving EMS to on-prem.