Handle remote services in topology view

[codefromthecrypt]

#128 introduced service topology of instrumented nodes. One issue with this is that an application that makes calls to remote services such as database and LLMs show up as a monolith and nothing else:

I'm not sure how other visualization products work, but possibly we can handle "db.system" or "gen_ai.system" to allow leaf spans to indicate who they are calling. I think there's a "peer.service" attribute, but it seems not in use in normal auto-instrumentation (at least in python)

While in the future this, ".system" thing may change, it gives a stable more usable bucket than hostname which is problematic, and more visually interesting.

Notes:

• java has a mapping but it can be tricky if hostnames or ports are not stable. Also this doesn't apply to python.
  https://opentelemetry.io/docs/zero-code/java/agent/instrumentation/#peer-service-name
• otel leads renamed X.system to X.system.name (where X in database, gen_ai, etc.), but it is likely that X.system will remain for years due to 3rd party or otherwise. So, maybe handle both.
  Consistent naming: db.system to db.system.name, namespace constants, remove db from system-specific names open-telemetry/semantic-conventions#1734