Maint: Remove CYBERGHOST_GROUP (change)

- It does not make any sense with newer server data
- It was to be deprecated anyway

internal/provider/utils/formatting.go

@@ -27,16 +27,6 @@ func NoServerFoundError(selection configuration.ServerSelection) (err error) {
 	}
 	messageParts = append(messageParts, "protocol "+protocol)
 
-	switch len(selection.Groups) {
-	case 0:
-	case 1:
-		part := "group " + selection.Groups[0]
-		messageParts = append(messageParts, part)
-	default:
-		part := "groups " + commaJoin(selection.Groups)
-		messageParts = append(messageParts, part)
-	}
-
 	switch len(selection.Countries) {
 	case 0:
 	case 1: