[FEATURE]: Opt out of service name defaulting

[jbw-vtl]

Package Name

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Package Version(s)

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Describe the goal of the feature

We are reviewing using ddtrace for user level / clientside / workstation level tracing of python library function usage.
These will be environments without DD_SERVICE defined and generally non service environment.

At some point over v3, ddtrace started automatically detecting service names based on e.g. the folder name of the command running the script, populating the base service field.
I understand this might be desirable for apps rather than having no service name / undefined-python-service, however sometimes this behaviour is not wanted and seems fairly intrusive.

We are explicitly sending the service tag in our custom traces which is being reported successfully, however would like to somehow opt-out / disable the base service detection for such environments.

Currently we are leveraging fairly invasive monkey patching & the wrapt library with a pattern such as below

@wrapt.when_imported("ddtrace.internal.schema")
def _patch_ddtrace_service_name_defaulting(ddtrace_internal_schema: ModuleType) -> None:
    ddtrace_internal_schema.DEFAULT_SPAN_SERVICE_NAME = None

Is your feature request related to a problem?

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Describe alternatives you've considered

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Additional context

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