drop table method should be registered in sql_clear_catalog.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@41896 20353a03-c40f-0410-a6d1-a30d3c3de9de

bt5/erp5_full_text_sphinxse_catalog/CatalogMethodTemplateItem/portal_catalog/erp5_mysql_innodb/z0_drop_sphinxse_index.catalog_keys.xml

 <catalog_method>
+ <item key="sql_clear_catalog" type="int">
+  <value>1</value>
+ </item>
 </catalog_method>