[FIX] hr: correct action source model

Should be from hr.employee
At a8326cc6 source model inconsistence was introduced but the bug was revealed
only after 55549f1e where it kept the wrong one

Fixes #20203

PS: this action should be removed in master in favor of hr_org_chart module

addons/hr/views/hr_views.xml

@@ -296,7 +296,7 @@
             <field name="domain">[('id','in',active_ids)]</field>
             <field name="view_type">tree</field>
             <field name="view_id" ref="view_partner_tree2"/>
-            <field name="binding_model_id" ref="base.model_res_partner"/>
+            <field name="binding_model_id" ref="hr.model_hr_employee"/>
         </record>
 
         <!-- Employee Category -->