[flask_instrumentor] dropping inbound propagation

Is your feature request related to a problem?

My problem is that I get weird long traces registered.
I believe this is because my customers are leaking traceparent and tracestate headers.

Describe the solution you'd like

I would like to be able to tell the FlaskInstrumentor to ignore inbound tracing properties.
That is, disabling inbound propagation.
Sadly, my infrastructure doesn't allow me to simply drop the headers, so I have to ignore the headers at my level.

Describe alternatives you've considered
I have considered customising the global propagator to strip out the information, but it's a bit unclear how to do it.
Here is a recent article I've found about it, in .NET: https://martinjt.me/2023/07/07/trace-propagation-and-public-api-endpoints-in-net-part-1-disable-all/

Additional context

• I cannot drop the requests using NGINX, Caddy or similar, since I don't have control over them in this setup 👀

Start by locating FlaskInstrumentor and the inbound propagation handling in the repository. Review how instrumentation options are exposed and how tracing headers are processed; done means FlaskInstrumentor can disable inbound propagation so leaked traceparent and tracestate headers do not affect incoming traces.