perf[cache]: init lazy cache after 6 seconds

net/src/main/java/com/zfoo/net/util/SingleCache.java

@@ -56,7 +56,7 @@ public class SingleCache<V> {
 
     public static <V> SingleCache<V> lazyBuild(long refreshDuration, Supplier<V> supplier) {
         var cache = new SingleCache<V>(refreshDuration, supplier);
-        cache.lazyRefreshDelay(18, TimeUnit.SECONDS);
+        cache.lazyRefreshDelay(6, TimeUnit.SECONDS);
         return cache;
     }