[REF] sale: get rid of 'Send email' context key

Purpose is to prepare improvements in emails sent in confirmation and payment.
A context key forcing email used only once in the code is removed. Method
used to send email is inlined. It allows to better understand flow.

Related to task ID 1873634
Linked to PR #28781

addons/sale/models/payment.py

@@ -87,7 +87,8 @@ class PaymentTransaction(models.Model):
         sales_orders = self.mapped('sale_order_ids').filtered(lambda so: so.state in ('draft', 'sent'))
         for so in sales_orders:
             # For loop because some override of action_confirm are ensure_one.
-            so.with_context(send_email=True).action_confirm()
+            so.action_confirm()
+            so.force_quotation_send()
         # invoice the sale orders if needed
         self._invoice_sale_orders()
         res = super(PaymentTransaction, self)._reconcile_after_transaction_done()

addons/sale/models/sale.py

@@ -674,9 +674,6 @@ class SaleOrder(models.Model):
             This method should be extended when the confirmation should generated
             other documents. In this method, the SO are in 'sale' state (not yet 'done').
         """
-        if self.env.context.get('send_email'):
-            self.force_quotation_send()
-
         # create an analytic account if at least an expense product
         for order in self:
             if any([expense_policy not in [False, 'no'] for expense_policy in order.order_line.mapped('product_id.expense_policy')]):