Make backends a pointer to avoid copies

[howardjohn]

Description

Reduce memory allocations by using pointers to large backend objects. This object is very frequently copied around and is large, resulting in substantial allocation pressure. See pprof -- the big chunk at the left is entirely removed with this change (note: the pprof is obscure due to generics, I promise it is from BackendObjectIR 🙂 )

Change Type

/kind cleanup

Changelog

NONE

Additional Notes

[Copilot]

Pull Request Overview

This PR changes the handling of backend objects by switching from passing large BackendObjectIR values to pointers in order to reduce memory allocations.

• Updated function signatures in the translator and policy index to accept pointers.
• Adjusted lambda conversions and collection types accordingly.

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
internal/kgateway/translator/irtranslator/backend.go	Changed method signature and related backend handling to pointers.
internal/kgateway/proxy_syncer/status.go	Modified generatePolicyReport to work with pointer types.
internal/kgateway/proxy_syncer/backends.go	Updated collection lambda to process backend pointers.
internal/kgateway/krtcollections/policy.go	Modified backend collections to use pointers and updated conversion.

[shashankram]

Failing test and needs DCO

 Error: internal/kgateway/translator/irtranslator/backend_test.go:42:43: cannot use backend (variable of struct type "github.com/kgateway-dev/kgateway/v2/internal/kgateway/ir".BackendObjectIR) as *"github.com/kgateway-dev/kgateway/v2/internal/kgateway/ir".BackendObjectIR value in argument to bt.TranslateBackend