atenet-router traces are detached + do not use ate.* attribute keys

[krisztianfekete]

Expected Behavior

One ResumeActor request should show up as a single connected trace across atenet-router -> ateapi -> atelet -> ateom, and the router spans should have the same ate.* attributes we standardized in #412.

Actual Behavior

You get two separate traces for the same request: one for the ateapi -> atelet -> ateom path, and a detached one with just the atenet-router spans (see Zoe Zhao (@zoez7)'s screenshots on #412). The trace context seemingly doesn't survive the router hop.

Additionally, the router spans use non-namespaced keys instead of the ate.* convention, e.g. atespace, actor_id, actor_template_namespace, actor_template_name, and outcome

Steps to Reproduce the Problem

1. Run the setup scripts
2. Run kubectl ate resume actor my-counter-1 -a demo --trace
3. Open Jaeger/similar, check the traces

Specifications

• Version: main
• Platform: all

[krsnaSuraj]

Opened PR #429 with the fix.

Changes:

1. resumer.go: Propagate callers span context through singleflight DoChan so otelgrpc picks up the parent - fixes the primary trace detachment
2. extproc.go: Inject traceparent/tracestate into ext_proc header mutation so the worker pod receives the same trace - fixes the secondary trace gap
3. Attribute renaming: All span and metric attributes now use ate.* namespace per the convention from PR feat(otel): set ate.* actor telemetry identity on ateapi spans #412