[Chore] Remove leftover meshery-octarine references from mesheryctl fixtures and Docs assets

Summary

meshery-extensions/meshery-octarine has been archived for years (Octarine itself was acquired and discontinued), but references remain in this repository.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 — L117, L125 (meshery-octarine-deployment.yaml, meshery-octarine-service.yaml)

Meshery Docs

• docs/content/en/project/compatibility-matrix/images/service-meshes/octarine.svg — remove once confirmed unreferenced by the matrix layouts

Out of scope

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

Note

layer5io/layer5 carries an already commented-out Octarine block in its handbook data; that is covered in layer5io/layer5#8075.