Remove dangling netty dependency management

We have a very old version of io.netty:netty dependency in our dependency management that
is not being used anyways. This commit removes this dependency management so that dependabot
does not report it as security vulnerability.

Signed-off-by: Boxuan Li <liboxuan@connect.hku.hk>
(cherry picked from commit 4685531)

pom.xml

@@ -923,11 +923,6 @@
                 <artifactId>netty</artifactId>
                 <version>3.2.10.Final</version>
             </dependency>
-            <dependency>
-                <groupId>io.netty</groupId>
-                <artifactId>netty</artifactId>
-                <version>3.10.6.Final</version>
-            </dependency>
 
             <!-- Spatial4j -->
             <dependency>