Relocated `istio-config` from `clusters/d8-ugmk-prod/infrastructure` into `infrastructure/istio-config/d8-ugmk-prod` overlay. Updated kustomization files to reference the new overlay structure. Removed unused patches and flattened resource definitions.
Relocate patches from clusters/d8-ugmk-prod/infrastructure/patches into
infrastructure/<module>/d8-ugmk-prod/ overlays (base + patches), matching
the apps/<app>/<cluster> and existing yc-k8s-test layout.
clusters/d8-ugmk-prod/infrastructure/kustomization.yaml now just references
the kafka, rabbitmq, camunda, vault, postgresql and zitadel overlays, with
no patches block. The patches/ directory is removed.
No rendered change: HelmRelease, namespace patches are preserved 1:1.
