EnforceServers feature broken after moving logic to the registry server

[dmartinol]

The MCPRegistry controller defines a server enforcement feature activated by the EnforceServers flag:

	// EnforceServers indicates whether MCPServers in this namespace must have their images
	// present in at least one registry in the namespace. When any registry in the namespace
	// has this field set to true, enforcement is enabled for the entire namespace.
	// MCPServers with images not found in any registry will be rejected.
	// When false (default), MCPServers can be deployed regardless of registry presence.
	// +kubebuilder:default=false
	// +optional
	EnforceServers bool `json:"enforceServers,omitempty"`

This feature is now broken after the recent refactory, because the checkImageInRegistry method should validate the image using the APIs instead of the data store (a ConfigMap, when it was initially developed).

Please consider to either disable this feature (and update the docs) or implementing it according t o the new design.

[dmartinol]

Another related issue: #2009