[Chore] Remove leftover meshery-cpx references from mesheryctl fixtures and UI assets

Summary

meshery-extensions/meshery-cpx (Citrix CPX Service Mesh) has been archived since 2023. #7146 tracked its removal and was closed in August 2023, but references remain in this repository. This issue covers clearing them.

The adapter repository is read-only, so this cleanup has no counterpart issue there. One issue per adapter; sibling issues are linked in a comment below.

mesheryctl

• mesheryctl/pkg/utils/fixtures/platform/listmanifest.api.response.golden — L29, L37 (meshery-cpx-deployment.yaml, meshery-cpx-service.yaml)

Meshery UI

• ui/public/static/img/adapters/citrix_service_mesh.svg, citrix_service_mesh-light.svg, citrix_service_mesh-white.svg and citrixservicemesh.svg — confirm each is unreferenced before deleting

Meshery Docs

• Leave the historical release notes (docs/content/en/project/releases/v0.6.6.md, v0.6.78.md) untouched — they are a record of past releases

Out of scope

The MeshType GraphQL enum value CITRIX_SERVICE_MESH stays; dropping enum values is a breaking API change requiring make graphql-build.

Note

The site repositories still advertise this adapter with a dead link; that is covered in meshery/meshery.io#2987 and layer5io/layer5#8075.