remove unused import

Author: vladak

plugins/LdapPlugin/test/opengrok/auth/plugin/LdapAttrPluginTest.java

@@ -33,7 +33,6 @@
 import java.util.TreeMap;
 import java.util.TreeSet;
 import javax.servlet.http.HttpServletRequest;
-import javax.servlet.http.HttpSession;
 import opengrok.auth.entity.LdapUser;
 import opengrok.auth.plugin.entity.User;
 import opengrok.auth.plugin.util.DummyHttpServletRequestLdap;