[Task]: Remove direct assess to Envoy Dynamic Metadata from Policies

Please select the area the issue is related to

Area/Gateway (Routing, API deployment in gateway etc.)

Please select the aspect the issue is related to

Aspect/API (API backends, definitions, contracts, interfaces, OpenAPI)

Description

$subject

Ex:

type ImmediateResponse struct {
	StatusCode            int
	Headers               map[string]string
	Body                  []byte
	AnalyticsMetadata     map[string]any            // Custom analytics metadata
	DynamicMetadata       map[string]map[string]any // Dynamic metadata by namespace <---------- HERE
	AnalyticsHeaderFilter DropHeaderAction          // Headers to exclude from analytics
}

type UpstreamRequestHeaderModifications struct {
	HeadersToSet    map[string]string // overwrite header (last write wins)
	HeadersToRemove []string          // remove by name (case-insensitive)

	// Routing mutations — applied before the request is forwarded to upstream.
	// These are valid at the header phase because routing decisions do not require
	// the request body to be available.
	UpstreamName            *string             // route to a named upstream definition (nil = no change)
	Path                    *string             // rewrite the request path (nil = no change)
	Host                    *string             // rewrite the :authority header (nil = no change)
	Method                  *string             // rewrite the request method (nil = no change)
	QueryParametersToAdd    map[string][]string // add or replace query parameters
	QueryParametersToRemove []string            // remove query parameters by name

	AnalyticsMetadata     map[string]any            // custom analytics metadata
	DynamicMetadata       map[string]map[string]any // dynamic metadata by namespace <---------- HERE
	AnalyticsHeaderFilter DropHeaderAction          // headers to exclude from analytics
}

No file, test, or entry point is named, and the description still contains the placeholder "$subject". First locate the policy and gateway API definitions exposing DynamicMetadata, then confirm the intended replacement or removal behavior with maintainers; done means policies no longer have direct access to Envoy Dynamic Metadata.