Handle `KongUpstreamPolicy` correctly for `HTTPRoute` using multiple services in backendRefs in one rule

[randmonkey]

Is there an existing issue for this?

• I have searched the existing issues

Does this enhancement require public documentation?

• I have added an Acceptance Criteria item for adding and/or adjusting public documentation (if applicable)

Problem Statement

Currently KongUpstreamPolicy is enabled by attaching to a Service in kubernetes by annotation konghq.com/upstream-policy. Then Kong upstreams translated from Ingress and HTTPRoute using the service as backend will apply the upstream policy.
It is OK in the case of Ingress, but HTTPRoute can use multiple services in backendRefs in a single rule. We need a proper way to attach a single KongUpstreamPolicy to the backendRefs and finally translate to correct upstream.

Proposed Solution

• Implement a proper way to attach a KongUpstreamPolicy to backendRef of a rule
• Translate the backendRefs to services and upstreams in Kong correctly
• Deprecate the annotations to attach KongUpstreamPolicy used with HTTPRoute

Additional information

No response

Acceptance Criteria

No response