ORC-2098: Exclude .mvn/maven.config for apache-rat-plugin

### What changes were proposed in this pull request?

This PR aims to exclude `.mvn/maven.config` for `apache-rat-plugin`.

### Why are the changes needed?

To avoid the build failures.

### How was this patch tested?

Pass the CIs.

### Was this patch authored or co-authored using generative AI tooling?

Generated-by: `Opus 4.6 (1M context)` on `Claude Code`

Closes #2539 from dongjoon-hyun/ORC-2098-2.1.

Authored-by: Dongjoon Hyun <dongjoon@apache.org>
Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>

Author: dongjoon-hyun

java/pom.xml

@@ -432,6 +432,7 @@
               <exclude>**/*.iml</exclude>
               <exclude>**/dependency-reduced-pom.xml</exclude>
               <exclude>.mvn/jvm.config</exclude>
+              <exclude>.mvn/maven.config</exclude>
             </excludes>
           </configuration>
           <executions>