The button to apply a custom group (Group By -> Add Custom Group -> Apply) was unreachable when using the keyboard. Remove the unnecessary attribute `tabindex="-1"` probably added for no apparent reason. closes odoo/odoo#37982 X-original-commit: 373c69bca366180601b760f05f219a4698e3c014 Signed-off-by: Luis González [Vauxoo] <luisg123v@users.noreply.github.com>