[FIX] correctly handle Sub KPI in qweb report

mis_builder/report/report_mis_report_instance.xml

@@ -10,23 +10,27 @@
               <h2 t-field="o.name"></h2>
               <table class="table table-condensed">
                 <thead>
-                  <tr>
                   <t t-foreach="docs_computed[o.id]['header']" t-as="h">
+                    <tr>
                       <th>
                         <div>
                           <t t-esc="h_value['kpi_name']"/>
                         </div>
                       </th>
-                      <th t-foreach="h_value['cols']" t-as="col" class="text-center">
+                      <t t-foreach="h_value['cols']" t-as="col">
+                        <th class="text-center" t-att-colspan="col.get('colspan', 1)">
                           <div>
                             <t t-esc="col['name']"/>
                           </div>
+                          <t t-if="col.get('date')">
                             <div>
                               <t t-esc="col['date']"/>
                             </div>
+                          </t>
                         </th>
                       </t>
                     </tr>
+                  </t>
                 </thead>
                 <tbody>
                   <tr t-foreach="docs_computed[o.id]['content']" t-as="c">