Fix web.xml file broken in []

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=117591773

java/com/google/domain/registry/env/common/backend/WEB-INF/web.xml

@@ -20,7 +20,6 @@
     and streaming it to cloud storage. Requests are sent here by App Engine after
     `RdeCreateCronServlet` enqueues a task specifying a URL that points to this servlet.
   -->
-  </servlet>
   <servlet-mapping>
     <servlet-name>backend-servlet</servlet-name>
     <url-pattern>/_dr/task/rdeStaging</url-pattern>