Ability to ignore trace propagation via traceparent/tracestate headers

Title: Ability to ignore trace propagation via traceparent/tracestate headers

Description: When using envoy as an edge-facing proxy, I would like to be able to configure it so that it ignores the traceparent header on incoming requests from the internet. This is because I do not want distributed tracing from outside systems.

[optional Relevant Links:] I raised a related issue in Envoy Gateway, where envoy is used as an edge-facing proxy.

The tracing module for nginx defaults to ignoring the traceparent header, and has configuration options for using it in trace propagation: https://nginx.org/en/docs/ngx_otel_module.html#otel_trace_context

What would be nice is the ability to conditionally propagate traces, depending on the value of the tracestate header like in Elastic API (specifically the restart_external option): https://github.com/elastic/apm/blob/main/specs/agents/trace-continuation.md