[tqlotel] Add priority keys parameter to the limit function.

[kovrus]

Description:

Add ability to specify attributes that aren't allowed to be dropped during limiting. Resolves #9734.

Link to tracking Issue:
#9734

Testing:

• Unit tests
• Running Otel collector locally with following configurations:

receivers:
  otlp:
    protocols:
      grpc:

exporters:
  logging:

processors:
  transform:
    traces:
      queries:
        - limit(attributes, 1, "http.url")
service:
  pipelines:
    traces:
      receivers: [otlp]
      processors: [transform]
      exporters: [logging]

and testing with

trace.set_tracer_provider(TracerProvider())
tracer = trace.get_tracer(__name__)
otlp_exporter = OTLPSpanExporter()
span_processor = BatchSpanProcessor(otlp_exporter)
trace.get_tracer_provider().add_span_processor(span_processor)

with tracer.start_as_current_span("foo") as span:
    span.set_attributes({
        SpanAttributes.HTTP_HOST: "",
        SpanAttributes.HTTP_METHOD: "",
        SpanAttributes.HTTP_STATUS_CODE: "",
        SpanAttributes.HTTP_TARGET: "",
        SpanAttributes.HTTP_CLIENT_IP: "",
        SpanAttributes.HTTP_URL: ""
    })

Documentation:
Updated:

• pkg/telemetryquerylanguage/functions/tqlotel/README.md
• processor/transformprocessor/README.md

[TylerHelmuth]

/cc @kentquirk

[kovrus]

@bogdandrutu @TylerHelmuth can you please review the PR?

[kentquirk]

This looks good.

I made one minor documentation suggestion.

[bogdandrutu]

Is not a list is a variadic argument. I mean this means we cannot add arguments after and we don't need to use join/concat/etc.

[bogdandrutu]

@TylerHelmuth how do we call these arguments?

[TylerHelmuth]

It is a limitation of the grammar at the moment. The grammar only supports 1 list parameter and it must be the last. Yes it is technically variadic, but I believe the docs currently call it a list. There is open issue to add full list capabilities.