chore: remove legacy OTEL forwarding

[tgmendes]

Summary

• Remove the raw OTLP body-tee middleware, forwarding worker, org-wide configuration service, and dashboard settings section.
• Remove the retired management API, generated CLI/SDK surface, and audit writer.
• Keep the project-scoped normalized OTLP relay introduced by feat: route normalized OTLP signals to project destinations #5939 as the only customer forwarding path.
• Leave the unused legacy database table in place for a separate migration-only contract PR.

Motivation

#5939 routes normalized logs, metrics, and traces through active project data-export routes, with destination headers and sensitive-data policy applied after normalization. Retaining the raw org-wide forwarder would duplicate delivery and preserve a competing configuration source. This stacked cleanup makes the normalized OTLP pipeline and data-export routes authoritative.

This is a hard cutover: existing org-wide forwarding rows are not migrated and stop taking effect. Active legacy configurations must have equivalent project data-export routes before merge.

[changeset-bot]

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Latest commit: caa7b17

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[cubic-dev-ai]

No issues found across 57 files

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[tgmendes]

Demo

What it shows:

1. The Logging & Telemetry page retains the organization telemetry controls.
2. The legacy OTEL forwarding destination form is no longer present; data-export routes own destination configuration.