[FIX] purchase_requisition : prevent creating purchase agreement from PO form

When you create a purchase agreement from the from view of a purchase order , it can have some invalid states which may lead to not having a vendor too.
Since choosing a purchase agreement makes the vendor read only on the PO form , then it may lead to having a PO form without a vendor and can't update it.

Steps to reproduce the error :
1- activate blanked orders
2- create a new purchase order directly from the PO form

opw-3335891

closes odoo/odoo#124528

X-original-commit: 100187e904b85306a7823c54adb78f493abacf78
Signed-off-by: Tiffany Chang <tic@odoo.com>
Signed-off-by: Mahdi Cheikh Rouhou (macr) <macr@odoo.com>

addons/purchase_requisition/views/purchase_views.xml

@@ -11,7 +11,8 @@
                 <field name="partner_id" widget="res_partner_many2one" context="{'res_partner_search_mode': 'supplier', 'show_vat': True}" attrs="{'readonly': ['|', ('is_quantity_copy', '=', 'none'), ('state', 'in', ['purchase', 'done', 'cancel'])]}" placeholder="Name, TIN, Email, or Reference" force_save="1"/>
             </field>
             <field name="partner_ref" position="after">
-                <field name="requisition_id" domain="[('state', 'in', ('in_progress', 'open', 'ongoing')), ('vendor_id', 'in', (partner_id, False)), ('company_id', '=', company_id)]"/>
+                <field name="requisition_id" domain="[('state', 'in', ('in_progress', 'open', 'ongoing')), ('vendor_id', 'in', (partner_id, False)), ('company_id', '=', company_id)]"
+                options="{'no_create': True}"/>
             </field>
             <xpath expr="//page[@name='purchase_delivery_invoice']" position="after">
                 <page string="Alternatives" name="alternative_pos">