Support explicit metric-remapping mode for future OSS/DDOT-compatible pipelines

[lucastemb]

Context

ADP's embedded OTLP ingest pipeline must preserve direct Core Agent behavior, so it leaves metric remapping disabled.

Embedded OTLP ingest
  kafka.producer.request-rate
  → kafka.producer.request-rate

The shared OTLP translator also supports exporter-compatibility remapping:

Exporter compatibility mode
  kafka.producer.request-rate
  → kafka.producer.request_rate
  + otel.kafka.producer.request-rate

That behavior is relevant to future OSS/DDOT-compatible exporter pipelines, not the current embedded ingest path.

Goal

Provide an explicit, pipeline-scoped way to construct OtlpMetricsTranslatorConfig with:

.with_remapping(true)

while keeping the embedded ADP OTLP ingest pipeline on its default false behavior.

Acceptance criteria

• Define the future exporter-compatibility pipeline/mode and its configuration owner.
• Enable remapping only for that explicit pipeline.
• Keep direct embedded OTLP ingest remapping-disabled.
• Document collision-prefix behavior and expected dashboard compatibility.
• Add targeted unit and integration coverage for each pipeline mode.

Non-goals

• Do not add otlp_config.metrics.with_remapping to the current embedded ingest configuration.
• Do not change normal ADP/Core Agent OTLP ingest parity.

Miscellaneous

Related to: #2074