[IMP] theme_bookstore: adapt s_banner

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

task-3097005

Part-of: odoo/design-themes#687

theme_bookstore/views/snippets/s_banner.xml

@@ -2,21 +2,13 @@
 <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-white-75"/>
-    </xpath>
-    <!-- Jumbotron -->
-    <xpath expr="//div[hasclass('jumbotron')]" position="attributes">
-        <attribute name="class" remove="o_cc o_cc1" separator=" "/>
-    </xpath>
     <!-- Title -->
     <xpath expr="//h1" position="replace" mode="inner">
         The best sellers <br/>of the year
     </xpath>
     <!-- Button -->
-    <xpath expr="//a[hasclass('btn')]/t" position="replace" mode="inner">
-        Discover it
+    <xpath expr="//a[hasclass('btn')]" position="replace" mode="inner">
+        Discover it <span class="fa fa-angle-right ms-2"/>
     </xpath>
 </template>