[IMP] base: no private filters by default

The custom filters created through the search view are still private by default
but the ir.filters created manually (e.g. through xml files) are most of the
time global.
In odoo core addons, all ir.filters defined add the line

   <field name="user_id" eval="False"/>

This should simplify the development while not changing the behaviour for
actual users.

Closes #8218

odoo/addons/base/models/ir_filters.py

@@ -13,7 +13,7 @@ class IrFilters(models.Model):
     _order = 'model_id, name, id desc'
 
     name = fields.Char(string='Filter Name', translate=True, required=True)
-    user_id = fields.Many2one('res.users', string='User', ondelete='cascade', default=lambda self: self._uid,
+    user_id = fields.Many2one('res.users', string='User', ondelete='cascade',
                               help="The user this filter is private to. When left empty the filter is public "
                                    "and available to all users.")
     domain = fields.Text(default='[]', required=True)