[FIX] l10n_ch: Unlink res.config.settings after init

Purpose
=======

If not unlinked, it could make it impossible to create a not null
constraint on columns that are installed after l10n_ch before the
garbage collector dropped the existing wizard, leading to an error
like the following:

Table 'res_config_settings': unable to set NOT NULL on column 'ebay_currency'

Part-of: odoo/odoo#105119

addons/l10n_ch/__init__.py

@@ -11,13 +11,13 @@ def init_settings(env):
     '''
     # The cash rounding is activated by default only if the company is localized in Switzerland or Liechtenstein.
     for company in env['res.company'].search([('partner_id.country_id.code', 'in', ["CH", "LI"])]):
-        res_config_id = env['res.config.settings'].create({
+        config_wizard = env['res.config.settings'].create({
             'company_id': company.id,
             'group_cash_rounding': True
         })
         # We need to call execute, otherwise the "implied_group" in fields are not processed.
-        res_config_id.execute()
-
+        config_wizard.execute()
+        config_wizard.unlink()
 
 def post_init(env):
     init_settings(env)