Remove scrollbar styles and related conditions from head.html

- Deprecates var `site.Params.assets.disableScrollBarStyle`

layouts/partials/head.html

@@ -42,11 +42,6 @@
 {{- $includes := slice }}
 {{- $includes = $includes | append (" " | resources.FromString "assets/css/includes-blank.css")}}
 
-{{- if not (eq site.Params.assets.disableScrollBarStyle true) }}
-    {{- $ScrollStyle := (resources.Get "css/includes/scroll-bar.css") }}
-    {{- $includes = (append $ScrollStyle $includes) }}
-{{- end }}
-
 {{- $includes_all := $includes | resources.Concat "assets/css/includes.css" }}
 
 {{- $theme_vars := (resources.Get "css/core/theme-vars.css") }}
@@ -139,12 +134,6 @@
             }
         }
 
-        @media (prefers-color-scheme: light) {
-            .list::-webkit-scrollbar-thumb {
-                border-color: var(--code-bg);
-            }
-        }
-
     </style>
     {{- end }}
 </noscript>