Send Kong traces to Tempo and gateway audit logs to Loki

Point OTEL_TRACES_ENDPOINT at Tempo instead of Jaeger. The variable is a
cluster-wide default, so this moves all five domains at once; Jaeger stays
deployed but no longer receives anything. Tempo derives RED span metrics
and the service graph from these traces on its own, and its trace ids
correlate with the audit logs below.

Add a Loki output to the audit collector. Kong's http-log payload is a
JSON object per request and Loki has no endpoint that accepts it, so
Fluent Bit is the translator between the two formats.

The `domain` label comes from $TAG, which the http input derives from the
request URI. That makes the path a domain posts to its identity here, so
one output block covers every domain and onboarding the next one is a
single AUDIT_LOG_ENDPOINT change on its side rather than another block.

The file output stays on Match * so the on-disk audit trail continues for
every domain, which keeps the switch reversible.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

kong-platform/dataplane-template-defaults.yaml

@@ -18,6 +18,9 @@ data:
   CORS_ORIGINS: https://*.sttlab.local
   RATE_LIMIT_MINUTE: "300"
   REQUEST_MAX_BODY_SIZE: "10" # MB
-  # Jaeger v2 (OTLP-native), Helm-installed 2026-08-20, ns observability,
-  # cluster-wide — shared by every domain, not domain-specific.
-  OTEL_TRACES_ENDPOINT: http://jaeger.observability.svc.cluster.local:4318/v1/traces
+  # Tempo (OTLP-native), ns observability, cluster-wide — shared by every
+  # domain, not domain-specific. Replaced Jaeger on 2026-08-25: Tempo is the
+  # trace backend of the infra-observability stack, so its span metrics feed
+  # Prometheus and its traces correlate with the Loki logs from the same
+  # requests. Jaeger is still deployed but no longer receives anything.
+  OTEL_TRACES_ENDPOINT: http://tempo.observability.svc.cluster.local:4318/v1/traces