[FIX] web: fix the scroll issue of kanban view with search panel

Currently in kanban view which contains search panel when user click
on kanban dropdown menu then a dropdown menu will be hidden due to
scrollbar of kanban view.

This issue arises from this commit:
https://github.com/odoo/odoo/commit/a95cbbd631a2fa9be62eb42cba43e853fdf4b789

closes odoo/odoo#49791

Task-id: 2204306
Closes: #47586
X-original-commit: d613bb8ba4f5a4d818592a80f4aee2ef67916bc0
Signed-off-by: Yannick Tivisse (yti) <yti@odoo.com>

addons/web/static/src/scss/kanban_view.scss

@@ -564,6 +564,8 @@
 
     // Kanban UN-grouped Layout
     &.o_kanban_ungrouped {
+        min-height: 100%;
+        align-content: flex-start;
         flex-flow: row wrap;
         justify-content: flex-start;