[FIX] website: remove duplicated filter option for blockquote

The blockquote in its "cover" layout allows to add a background with
a dedicated colored filter on top of it. That option was a bit buggy
since the filter option only appeared if the page was saved first. As
we now have a generic option to apply a colored filter on image
themselves, that option became useless anyway.

Part of https://github.com/odoo/odoo/pull/53930
task-2157252

addons/website/static/src/snippets/s_blockquote/000.scss

@@ -42,10 +42,10 @@
         p:last-of-type {
             margin-bottom: $spacer * .5;
         }
+        // Compatibility
         .s_blockquote_filter {
             padding: $spacer * 3 $spacer * 2 $spacer * 2;
         }
-        // Compatibility
         .quote_char {
             margin: $spacer * 2 0 $spacer 0;
             & ~ .blockquote-footer {

addons/website/static/src/snippets/s_blockquote/options.js

@@ -25,14 +25,11 @@ options.registry.Blockquote = options.Class.extend({
             $blockquote.css({"background-image": "url('/web/image/website.s_blockquote_cover_default_image')"});
             $blockquote.css({"background-position": "50% 50%"});
             $blockquote.addClass('oe_img_bg');
-            if (this.$target.find('.s_blockquote_filter').length == 0) {
-                $blockquote.wrapInner('<div class="s_blockquote_filter bg-white-50"/>');
-            }
         } else {
             $blockquote.css({"background-image": ""});
             $blockquote.css({"background-position": ""});
             $blockquote.removeClass('oe_img_bg');
-            $blockquote.find('.s_blockquote_filter').contents().unwrap();
+            $blockquote.find('.s_blockquote_filter').contents().unwrap(); // Compatibility
         }
 
         // Minimalist

addons/website/views/snippets/s_blockquote.xml

@@ -34,19 +34,11 @@
             <t t-set="images_dependencies" t-value="'blockquote_cover_opt'"/>
         </t>
 
-        <!-- Filter -->
-        <div data-selector=".s_blockquote" data-target=".s_blockquote_filter">
-            <we-colorpicker string="Filter"
-                data-select-style="true"
-                data-css-property="background-color"
-                data-color-prefix="bg-"
-                data-excluded="common, theme, custom"
-                data-dependencies="blockquote_cover_opt"/>
-        </div>
         <!-- Shadow -->
         <div data-js="Box" data-selector=".s_blockquote" data-target=".s_blockquote_content">
             <t t-call="website.snippet_options_shadow_widgets"/>
         </div>
+
         <!-- Border Color -->
         <div data-selector="blockquote">
             <we-colorpicker string="Border Color"