[Infra UI] Improve results when querying for common fields between datasets in Inventory UI

[neptunian]

When grouping or filtering by a field outside the system datasets no results are returned because they need to be joined. Example when filtering/grouping by service.name:

Solution would be to adjust the query like to function similar to Hosts UI where we get the first get host.names from the documents that have service.name and then pass those to query their respectric metrics within the system datasets.

Something to keep in mind is the Hosts UI is limited in how many hosts will be fetched but the Inventory UI is a composite aggregation. How big of a list of hosts could we send? It may not be feasible unless we limit the amount of hosts we show the user.

[elasticmachine]

Pinging @elastic/obs-ux-infra_services-team (Team:obs-ux-infra_services)

[roshan-elastic]

Hey @smith,

Does this need refining? I'm thinking it could be a good spike to explore whether this solves the problem and measure the change in performance?

Not sure how to prioritisie this in GitHub but I'd love to do this after we've delivered the current queue of items after the whip limit opens up a spot.

[smith]

@roshan-elastic I've added it to refining so we can determine the best approach.