[FIX] website: fix vertical header template elements ordering (BS5)

With the merge of Bootstrap 5 at [1], the class "order-lg-12" no longer
exists, this class was used in the vertical template header and this one
was therefore broken. This commit replaces this class with "order-lg-5"
to fix that.

Note: while this commit was being made, [2] was merged restoring the
order-lg-12 class into BS5. This commit is still merged as using
order-lg-5 instead cannot hurt and is a bit more robust in case [2] is
reverted for some reason.

[1]: https://github.com/odoo/odoo/commit/971e5a91aab96d36129a823e03f1f9f1b1293968
[2]: https://github.com/odoo/odoo/commit/6ed6a512bfec8e2415da2d19304215fcd06273b2

closes odoo/odoo#98028

Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

addons/website/views/website_templates.xml

@@ -504,7 +504,7 @@
                         </t>
                         <!-- Nav -->
                         <t t-call="website.navbar_nav">
-                            <t t-set="_nav_class" t-valuef="mx-auto order-first order-lg-12"/>
+                            <t t-set="_nav_class" t-valuef="mx-auto order-first order-lg-5"/>
                             <!-- Menu -->
                             <t t-foreach="website.menu_id.child_id" t-as="submenu">
                                 <t t-call="website.submenu">