agent-platform release v4.57.2

The agentgateway data plane exports traces: the connectivity chart renders a Gateway-scoped -tracing policy, its egress policy and the tenant pod label (giantswarm/giantswarm#36711). The proxy reads OTEL_EXPORTER_OTLP_* only as overrides of a tracing configuration, so the env of gateway.parameters.dataPlaneEnv started no exporter and no data-plane span reached Tempo. New: AgentgatewayPolicy <release>-tracing on the data-plane Gateway with frontend.tracing to the endpoint and protocol the env names (global.observability.traces.otlp wins when its endpoint is set), at agentgateway’s default sampling: a request with a sampled traceparent is traced, one without is not. <release>-dataplane-otlp-egress allows DNS plus the endpoint’s namespace on its port, in both policy flavours. The exporter sends no headers, so the new gateway.parameters.podLabels carries observability.giantswarm.io/tenant: giantswarm from the meta chart, the label otlp-gateway routes by. verify-metric-labels now counts templates with a frontend.metrics section, not any frontend section. make verify-dataplane-tracing asserts all of it. Every installation with the agentgateway data plane gets two new objects and rolls the data-plane pods once (the pod label).