[FIX] point_of_sale: cannot scroll in categories

Current behaviour:
When there is too many product categories,
you cannot see the last items, because
the scrollbar is hidden.
This was made to hide the scrollbar on mobile.

Steps to reproduce:
1. Go to Point of Sale
2. Configuration > PoS Product Categories
3. Duplicate one category 12 times
4. Uncheck Restrict Categories
5. Dashboard > New Session
6. The list of categories is too long
7. Cannot see the last items

Cause of the issue:
Introduced by https://github.com/odoo/odoo/commit/60f41b1f831248c58f554dbe40114ef0d4ce42c0#diff-f23069b3927b8544dd51433e277cf8b650b10a67e5b8648155e427aaa31c19a3R838

Fix:
Make the scrollbar disappear on mobile,
and appear otherwise.

opw-3653429

closes odoo/odoo#150154

X-original-commit: 0f7fbede653dcb7c91536ea9c87df7d831a0c8cf
Signed-off-by: Joseph Caburnay (jcb) <jcb@odoo.com>

addons/point_of_sale/static/src/app/screens/product_screen/product_list/product_list.scss

@@ -11,3 +11,12 @@
 .button-no-demo {
     color: #017e84 !important;
 }
+
+.scrollbar-hidden {
+    -ms-overflow-style: none;
+    scrollbar-width: none;
+
+    &::-webkit-scrollbar {
+        display: none;
+    }
+}

addons/point_of_sale/static/src/app/screens/product_screen/product_list/product_list.xml

@@ -9,6 +9,7 @@
                     categories="getCategories()"
                     onClick="(id) => this.pos.setSelectedCategoryId(id)"
                     showImage="showCategoryImages"
+                    class="ui.isSmall ? 'scrollbar-hidden' : ''"
                 />
                 <Input tModel="[pos, 'searchProductWord']"
                     class="'p-2'"