This commit simplifies the component SCSS improving bootstrap integration and allowing components other than 'SearchPanel' to use the same tree-view design. Part of the overall v16 SCSS optimization/restyle, task-2704984. task-2795166 closes odoo/odoo#87687 Related: odoo/enterprise#25781 Signed-off-by: Pierre Paridans (app) <app@odoo.com>