perf[protocol]: 简化获取ProtocolRegistration，提高性能

protocol/src/main/java/com/zfoo/protocol/ProtocolManager.java

@@ -70,9 +70,7 @@ public class ProtocolManager {
     }
 
     public static IProtocolRegistration getProtocol(short protocolId) {
-        var protocol = protocols[protocolId];
-        AssertionUtils.notNull(protocol, "[protocolId:{}]协议不存在，可能没有注册该协议或者协议号错误", protocolId);
-        return protocol;
+        return protocols[protocolId];
     }
 
     public static ProtocolModule moduleByProtocolId(short id) {