[FIX] website: better helper for domain in settings

If the user type his website URL as suggested by the helper, and he redirects
his `http` to `https` (nginx, cloudflare..), then his canonical url won't ever
be reachable.
Most critical issue will be that we won't display the `alternate/hreflang` tag,
which basically tells the search engines what and where is our translated
content.

opw-2486918

closes odoo/odoo#69093

X-original-commit: 15bf30b7b5312a943772ece20303e215b1ed6f6c
Signed-off-by: Jérémy Kersten (jke) <jke@openerp.com>
Signed-off-by: Romain Derie <rdeodoo@users.noreply.github.com>

addons/website/views/res_config_settings_views.xml

@@ -103,7 +103,7 @@
                                         Display this website when users visit this domain
                                     </div>
                                     <div class="mt8">
-                                        <field name="website_domain" placeholder="www.odoo.com"/>
+                                        <field name="website_domain" placeholder="https://www.odoo.com"/>
                                     </div>
                                     <div groups="base.group_no_one">
                                         <div class="mt8 text-muted" title="You can have 2 websites with same domain AND a condition on country group to select wich website use.">