[IMP] theme_clean: adapt s_banner

Since the redesign of the original banner snippet, the customizations
made in theme_clean have had to be adapted.

task-3097005

Part-of: odoo/design-themes#687

theme_clean/views/snippets/s_banner.xml

@@ -1,11 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<odoo>
-
-<template id="s_banner" inherit_id="website.s_banner">
-    <!-- Filter -->
-    <xpath expr="//div[hasclass('container')]" position="before">
-        <div class="o_we_bg_filter bg-black-50"/>
-    </xpath>
-</template>
-
-</odoo>