[FIX] web: correctly update modifiers in editable list with buttons

Since rev. odoo/odoo@015958d it is possible to add buttons in list group
headers. These buttons are defined in <groupby> nodes, pointing to m2o
fields. Modifiers specified on these buttons thus use fields on the m2o
comodel.

There was a traceback in editable list view, when grouping by a m2o
that defines a groupby button with modifiers as the modifiers are not
registered with the same datapoint. When updating the modifiers, one
must ensure that the modifier are related to the updated record.

closes odoo/odoo#32456

Signed-off-by: Aaron Bohy (aab) <aab@odoo.com>