Optimize Netty dependency of cluster modules

- use `netty-handler` instead to reduce size

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

sentinel-cluster/pom.xml

@@ -27,6 +27,11 @@
 
     <dependencyManagement>
         <dependencies>
+            <dependency>
+                <groupId>io.netty</groupId>
+                <artifactId>netty-handler</artifactId>
+                <version>${netty.version}</version>
+            </dependency>
             <dependency>
                 <groupId>io.netty</groupId>
                 <artifactId>netty-all</artifactId>

sentinel-cluster/sentinel-cluster-client-default/pom.xml

@@ -29,7 +29,7 @@
 
         <dependency>
             <groupId>io.netty</groupId>
-            <artifactId>netty-all</artifactId>
+            <artifactId>netty-handler</artifactId>
         </dependency>
 
         <dependency>

sentinel-cluster/sentinel-cluster-server-default/pom.xml

@@ -33,7 +33,7 @@
 
         <dependency>
             <groupId>io.netty</groupId>
-            <artifactId>netty-all</artifactId>
+            <artifactId>netty-handler</artifactId>
         </dependency>
 
         <dependency>