[FIX] website: generate language selector only when needed

This commit generates the language selector element only when multiple
languages exist, avoiding an empty header list item that creates
an unnecessary border or empty space.

task-5150808

closes odoo#231256

Signed-off-by: Romaric Moyeuvre (romo) <[email protected]>

Author: ldau-odoo

addons/website/views/website_templates.xml

@@ -1045,8 +1045,8 @@
                 <div class="o_header_hide_on_scroll">
                     <div aria-label="Top" t-if="is_view_active('website.header_text_element') or is_view_active('website.header_social_links') or is_view_active('website.header_language_selector')" class="o_header_sales_two_top py-1">
                         <ul class="navbar-nav container d-grid h-100 px-3 o_grid_header_3_cols">
-                            <!-- Return empty placeholder if the element is not active to keep the right layout -->
-                            <li class="o_header_sales_two_lang_selector_placeholder" t-if="is_view_active('website.header_language_selector') == False"/>
+                            <!-- Return empty placeholder if the element is not active or if there is only one language to keep the right layout -->
+                            <li class="o_header_sales_two_lang_selector_placeholder" t-if="is_view_active('website.header_language_selector') == False or len(languages) == 1"/>
                             <!-- Language Selector -->
                             <t t-call="website.placeholder_header_language_selector">
                                 <t t-set="_div_classes" t-valuef="d-flex align-items-center h-100"/>
@@ -2179,7 +2179,7 @@
 
 <template id="header_language_selector" inherit_id="website.placeholder_header_language_selector" name="Header Language Selector" active="True">
     <xpath expr="." position="inside">
-        <li data-name="Language Selector" t-attf-class="o_header_language_selector #{_item_class}">
+        <li t-if="len(languages) > 1" data-name="Language Selector" t-attf-class="o_header_language_selector #{_item_class}">
             <t id="header_language_selector_call" t-call="portal.language_selector">
                 <t t-set="_div_classes" t-value="(_div_classes or '') + ' dropdown'"/>
             </t>