MNEMONIC-668: Obsolete java arg line due to JDK14 migration removed

Signed-off-by: Chunyong He <chunyong.he@gmail.com>
diff --git a/mnemonic-benches/mnemonic-sort-bench/pom.xml b/mnemonic-benches/mnemonic-sort-bench/pom.xml
index 8d9a452..1bfb420 100644
--- a/mnemonic-benches/mnemonic-sort-bench/pom.xml
+++ b/mnemonic-benches/mnemonic-sort-bench/pom.xml
@@ -154,7 +154,6 @@
             <configuration>
               <executable>java</executable>
               <arguments>
-                <argument>-Djava.ext.dirs=${project.build.directory}/service-dist</argument>
                 <argument>-ea</argument>
                 <argument>-classpath</argument>
                 <classpath />