Add service.framework.name to transaction metrics

The APM UI use `service.framework.name` to populate the service details dropdown menu. However, this field is not available on transaction metrics, meaning that we have to query raw events to populate the menu, which is slower. If we add `service.framework.name` to tx metrics we should be able to query tx metrics only. (I think it's a good guiding principle to add all fields that the UI uses by default to tx metrics, with some exceptions - but generally the UI should work without any sampled transactions at all).

No file, test, or entry point is named in the issue. Start by locating transaction-metrics generation and the existing handling of service.framework.name, then trace how the APM UI queries service details. Done means transaction metrics expose service.framework.name so the dropdown can be populated without querying raw events.

Written by the indexing model from the issue text.