[FIX] theme_*: enable footer/header template correctly

See [1], `enable_view()` is now in charge of disabling the already possibly
existing template header (and/or footer).
Disabling `website.template_header_default` was not enough, any of the other
template could have been selected by the user before updating the theme.

Note that when installing a theme the first time on a website, the error won't
occur as `_reset_default_config()` will be called through `_theme_remove()`.

[1]: https://github.com/odoo/odoo/pull/81181

Fixes https://github.com/odoo/upgrade/pull/3048
task-2593407
opw-2680866
opw-2685951
opw-2685124
opw-2679040

closes odoo/design-themes#536

Related: odoo/odoo#81181
Signed-off-by: Romain Derie (rde) <rde@odoo.com>

theme_notes/models/theme_notes.py

@@ -6,9 +6,4 @@ class ThemeNotes(models.AbstractModel):
 
     def _theme_notes_post_copy(self, mod):
         self.enable_header_off_canvas()
-
-        self.disable_view('website.footer_custom')
         self.enable_view('website.template_footer_descriptive')
-
-        # For compatibility
-        # self.enable_asset('theme_common.compatibility_saas_10_1')