weldr: fix minor inefficiency in composeStatusHandler

`uuids` was initialized with a length, but only appended to. This lead
to a slice with lots of empty uuids, followed by the actual ones.

Fix this by initializing to an empty slice.

This happened to work because there's a non-fatal check for non-existing
composes further down, and the empty string fails that test.

internal/weldr/api.go

@@ -1634,9 +1634,8 @@ func (api *API) composeStatusHandler(writer http.ResponseWriter, request *http.R
 	var uuids []uuid.UUID
 
 	if uuidsParam != "*" {
-		uuidStrings := strings.Split(uuidsParam, ",")
-		uuids = make([]uuid.UUID, len(uuidStrings))
-		for _, uuidString := range uuidStrings {
+		uuids = []uuid.UUID{}
+		for _, uuidString := range strings.Split(uuidsParam, ",") {
 			id, err := uuid.Parse(uuidString)
 			if err != nil {
 				errors := responseError{