[FIX] website_blog: adjust the width of the border when inside column

Steps to reproduce the bug:
- Go on the blog of the website.
- Edit.
- In the "Customize" section, apply the "List" "Layout" and activate
the "Sidebar".

-> The sidebar appears at the bottom of the page instead of on the
side.

The situation looks like this:
```html
<div class="container">
    <div class="row">
        <div class="col"></div>
        <div class="border-end"></div>
        <div class="col-12"></div>
    </div>
</div>
```
The bug comes from the fact that the `div` with the `border-end` class
is inside a `row` class. Due to that, a bootstrap 5 css rule applies
and puts the `width` of the `div.border-end` element to `100%`. Because
the element tries to fill the entire width of the `div.row`, it is put
at the bottom of the page as well as its following elements (in this
case, the sidebar). This bug is fixed by removing the `div.border-end`
element.

opw-3217775

closes odoo/odoo#117849

X-original-commit: 9d8b895b934e5b0986c932837fd043cf847a8992
Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

addons/website_blog/views/website_blog_templates.xml

@@ -171,7 +171,6 @@ list of filtered posts (by date or tag).
 <!-- (Option) Blog: Sidebar : Show -->
 <template id="opt_blog_sidebar_show" name="Show Sidebar" inherit_id="website_blog.blog_post_short" active="False">
     <xpath expr="//div[@id='o_wblog_posts_loop_container']" position="after">
-        <div t-if="opt_blog_list_view" class="border-end d-none d-lg-block" style="opacity: 0.5"/>
         <div t-attf-class="col-12 col-md-3 d-flex #{opt_blog_list_view and 'col-lg-4' or 'ms-lg-5'}">
             <t t-call="website_blog.sidebar_blog_index"/>
         </div>