Editable computed fields need to have their own compute
method.
Otherwise, when providing one of the two fields at create/write time
will not be taken into account because the compute method will be
triggered for the other field.
closesodoo/odoo#77912
X-original-commit: e35dc4c87821bbb668657eed99bb51c1f853c208
Related: odoo/enterprise#21685
Signed-off-by: William André (wan) <wan@odoo.com>