[REF] website_payment: remove website published mixin on payment acquirer

Indeed payment module already adds a website_published button to ease
acquirer management directly in payment without link to website. The
mixin added in website_payment adds a website_url field that has no use
for payment acquirers and is not used at all in the current codebase.
As there is no website url the website publish button method is not
different than the one already implemented in payment. There is
therefore no need for this override, lessening model code in
website payment.

addons/website_payment/models/__init__.py

@@ -1,2 +1 @@
-from . import payment
 from . import website

addons/website_payment/models/payment.py

@@ -1,7 +0,0 @@
-# -*- coding: utf-8 -*-
-# Part of Odoo. See LICENSE file for full copyright and licensing details.
-from odoo import api, fields, models
-
-class PaymentAcquirer(models.Model):
-    _name = 'payment.acquirer'
-    _inherit = ['payment.acquirer','website.published.mixin']