TracingService: `propagation_modes` incompatible with `opentelemetry` driver

[miguelvr]

Describe the bug Emissary ingress pod enters CrashLoopBackoff when propagation_modes is specified with driver: opentelemetry.

Also, the documentation hints that the way to specify propagation modes is spec.propagation_modes, when in reality it is spec.config.propagation_modes.

To Reproduce

1. Apply the following TracingService:

   apiVersion: getambassador.io/v3alpha1
   kind: TracingService
   metadata:
   name: tracing
   namespace: emissary
   spec:
   driver: opentelemetry
   service: opentelemetry-collector.opentelemetry:4317
   config:
   service_name: emissary
   propagation_modes: [TRACE_CONTEXT]
   sampling:
   overall: 100

2. Restart emissary-ingress deployment
3. Observe the CrashLoopBackOff

Expected behavior

• propagation_modes to be supported with opentelemetry driver
• emissary-ingress pod to restart successfully

Versions (please complete the following information):

• Ambassador: v3.9.1
• Kubernetes environment: Google Kubernetes Engine
• Version: v1.25.13-gke.20