Trace gateway should harmonize span errors recorded by Envoy

[a-thaler]

Description
The envoy proxy used by Istio is not following the semantic conventions of OTel properly. Especially one convention is ignored with an overall effect of the usability of the span data, which is about setting the error status in the spans status attribute in case of an error. Instead of setting the error status properly as outlined in https://opentelemetry.io/docs/concepts/signals/traces/#span-status, it introduces a custom boolean attribute "error" as outlined also in https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/observability/tracing#what-data-each-trace-contains.

Instead of introducing custom transformation support and asking every user to add a transformation as workaround, these should happen by default as part of the gateway features.

Goal: Add a transformation for spans which are instrumented by Envoy (as a first clazz citizen of Kyma) which sets the span status to error in case of envoys custom attribute is present.

Criterias:

• spans emitted by envoy (check instrumentation scope for example) are getting enriched the status "error" in case Envoy custom attribute "error=true" is present on the span
• if any status is set already, the feature will have no effect
• E2E tests are assuring the compatibility
• documentation is added

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