SharePointRESTConnector: fix delete attachments
<field name="sp_site" type="string" indexed="true" stored="true" multiValued="false"/>
<field name="sp_item" type="string" indexed="true" stored="true" multiValued="false"/>
<field name="sp_parentids" type="string" indexed="true" stored="true" multiValued="true"/>
+ <field name="sp_attachments" type="string" indexed="true" stored="true" multiValued="true"/>
<!-- O365 fields -->
<field name="o365_attachments" type="string" indexed="true" stored="true" multiValued="true"/>
