stream/mts/meta/meta.go: using copy instead of append to remove key from order slice in Meta.Delete()

stream/mts/meta/meta.go

@@ -120,7 +120,8 @@ func (m *Metadata) Delete(key string) error {
 		delete(m.data, key)
 		for i, k := range m.order {
 			if k == key {
-				m.order = append(m.order[:i], m.order[i+1:]...)
+				copy(m.order[:i], m.order[i+1:])
+				m.order = m.order[:len(m.order)-1]
 				break
 			}
 		}