Remove outdated comment

The problems with tidy-maven-plugin should have been fixed by
https://github.com/apache/axis-axis2-java-core/commit/83d7d473678995ec14b12e80936ca185a1f2a149.
diff --git a/pom.xml b/pom.xml
index f56d633..f703a16 100644
--- a/pom.xml
+++ b/pom.xml
@@ -1579,8 +1579,6 @@
                     </bundles>
                 </configuration>
             </plugin>
-            <!-- FIXME , what is wrong with systests/echo/pom.xml ? 
-            -->
             <plugin>
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>tidy-maven-plugin</artifactId>