MonoVertex Card always shows health status as "healthy"

[adarsh0728]

Currently health status is hardcoded as healthy for MonoVertex in UI.

numaflow/ui/src/components/pages/Namespace/partials/MonoVertexCard/index.tsx

Line 474 in d84980e

<span>{StatusString["healthy"]}</span>

Also mentioned in PR as a TODO.
Creating the issue for tracking.