Proposed title of this feature request

Data discovery for multiple backend scenarios

What is the nature and description of the request?

In a scenario in which multiple instances of observability data coexist (e.g. multiple Tempo instances), some functionality that needs to retrieve data needs to know in advance where to look for it. Examples of this are:

• UI accessing observability signals for a particular pod
• Korrel8r efficiently accessing a particular backend (now it hardcodes the Tempo instance)

Notes:

• From https://docs.google.com/document/d/1QGHIvzCbl6X6Nll6Ic6WOKbGQMUve8j9kE_jHlUpebI/edit#heading=h.66iaru62jsz4 
  For Prometheus/Thanos, there's a Labels api that could make looking up for the existence of a label (e.g. pod name) very cheap.
• Tenancy should be taken into account, since not all users have access to all backends.
• Tempo has rate limiting per tenant.
• OTELcol proposal for rate limiting extension https://github.com/open-telemetry/opentelemetry-collector-contrib/issues/6908

Why does the customer need this? (List the business requirements)

Implementing an efficient pattern will help performance of our solutions 

List any affected packages or components.

• Backends: Tempo/Loki/MonitoringStack
• UI
• Korrel8r