[HUDI-4135] remove netty and netty-all (apache#5663)

Author: liujinhui1994

hudi-spark-datasource/hudi-spark2/pom.xml

@@ -203,19 +203,6 @@
       <optional>true</optional>
     </dependency>
 
-    <dependency>
-      <groupId>io.netty</groupId>
-      <artifactId>netty</artifactId>
-      <version>3.9.9.Final</version>
-      <optional>true</optional>
-    </dependency>
-    <dependency>
-      <groupId>io.netty</groupId>
-      <artifactId>netty-all</artifactId>
-      <version>4.1.17.Final</version>
-      <optional>true</optional>
-    </dependency>
-
     <!-- Hoodie - Test -->
     <dependency>
       <groupId>org.apache.hudi</groupId>