[FIX] website: set db_name on MockRequest

Commit [1] broke the standalone tour of website's themes, which is run
in nightly only (sadly).
That tour was added a few months ago with [2] which was tested the fix
done by [3].

[1]: https://github.com/odoo/odoo/commit/fcf6e462e116d13533014e31d4191763354811cf
[2]: https://github.com/odoo/design-themes/commit/0e324061d1c4437ef19d07f23eaf5663cb8fe657
[3]: https://github.com/odoo/odoo/commit/bed3cd54a5c7baeab173129036246bef543eef94

closes odoo/odoo#102670

X-original-commit: 326d33f129d73ed2b703b3a7173386e99f88b4d8
Signed-off-by: Romain Derie (rde) <rde@odoo.com>

addons/website/tools.py

@@ -52,7 +52,7 @@ def MockRequest(
             website_sale_current_pl=website_sale_current_pl,
         ),
         geoip={},
-        db=None,
+        db=env.registry.db_name,
         env=env,
         registry=env.registry,
         cr=env.cr,