Ability to control trace ID length on Zipkin

[Stono]

Describe the feature request
The envoy configuration for type.googleapis.com/envoy.config.trace.v3.ZipkinConfig allows you to configure trace_id_128bit, which in istio defaults to true.

I'd like to be able to control this to set it to false, so that traceid's generated by istio align with traceid's generated from some of our other systems (64 bit).

Guessing it'd need to be an option on https://istio.io/latest/docs/reference/config/istio.mesh.v1alpha1/#MeshConfig-ExtensionProvider-ZipkinTracingProvider

Describe alternatives you've considered

None, i don't see a way that I can control this other than using an EnvoyFilter to inject the tracer directly myself which seems counter-productive to the 1st class API.

There's also talk of doing custom bootstrap here: #37517, but again that seems a bit of a hammer for something that should now be configurable via the telemetry api? I did give it a go... but it didn't seem to work anyway.

apiVersion: v1
kind: ConfigMap
metadata:
  name: istio-custom-bootstrap-config
  namespace: istio-system
data:
  custom_bootstrap.json: |
    "tracing": {
      "http": {
        "name": "envoy.tracers.zipkin",
        "typed_config": {
          "@type": "type.googleapis.com/envoy.config.trace.v3.ZipkinConfig",
          "collector_cluster": "zipkin",
          "collector_endpoint": "/api/v2/spans",
          "trace_id_128bit": false,
          "shared_span_context": false,
          "collector_endpoint_version": "HTTP_JSON"
        }
      }
    }

Affected product area (please put an X in all that apply)

[ ] Ambient
[ ] Docs
[ ] Installation
[ ] Networking
[ ] Performance and Scalability
[x] Extensions and Telemetry
[ ] Security
[ ] Test and Release
[ ] User Experience
[ ] Developer Infrastructure

Affected features (please put an X in all that apply)

[ ] Multi Cluster
[ ] Virtual Machine
[ ] Multi Control Plane

Additional context

[ramaraochavali]

@zirain

[zirain]

will take a look tomorrow