[FIX] website_blog: hide content width button in blog context

The user was not able to change the width of the first content of a blog
because it's not part of a blog.

This commit will hide content width option for every content in a blog
post.

Part of https://github.com/odoo/odoo/pull/68823
task-2446852

X-original-commit: 85051e88707e61b7d3756a666236386c5056ed19

addons/website_blog/views/snippets/snippets.xml

@@ -21,5 +21,10 @@
     <xpath expr="//*[@data-js='anchor']" position="attributes">
         <attribute name="data-exclude" add=".o_wblog_post_content_field > :not(div, section)" separator=","/>
     </xpath>
+
+    <!-- Hides ContainerWidth option for content in blog posts -->
+    <xpath expr="//div[@data-js='ContainerWidth']" position="attributes">
+        <attribute name="data-exclude" add="#o_wblog_post_content *" separator=","/>
+    </xpath>
 </template>
 </odoo>