[Feat]: Support disabling A2A OTEL Instrumentation

[vinoo999]

Is your feature request related to a problem? Please describe.

The A2A server instrumentation for OpenTelemetry spans is too verbose. The current way to disable A2A spans is to disable at the export level. The current library disables instrumentation based on import error only

Describe the solution you'd like

What I would like to do is disable this at the instrumentation level rather than the export level. This can be done in a few ways; one that may be most simple to users is to configure an environment variable A2A_OTEL_INSTRUMENTATION that supports disabling spans for the a2a python library

Describe alternatives you've considered

• Custom exporter that filters out a2a.server.* spans; this is an antipattern and can cause broken trace trees
• Injecting a custom tracer provider for the a2a-python module

Additional context

#295 identifies that tracing is only done if a tracer is configured. The underlying issue around noisy tracing or disabling tracing is not addressed.

Code of Conduct

• I agree to follow this project's Code of Conduct

[lkawka]

Hi vinoo999,

It makes sense to allow for explicitly disabling the OTEL tracing. I like the env variable approach you described above. However, we can't prioritize this work now. Feel free to create a PR for this.

[aabmass]

• Custom exporter that filters out a2a.server.* spans; this is an antipattern and can cause broken trace trees

FYI open-telemetry/opentelemetry-python#4861 will let you disable specific instrumentations. The environment variable seems like a good stop gap though.