[IMP] mail: have replace as default command on update

[rapr-odoo]

Current behavior before PR:

There should be a replace command as default while updating a field.

Desired behavior after PR is merged:

If there is no command passed while updating a field then, add a replace command as default

Task-2851488

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[robodoo]

Pull request status dashboard.

[seb-odoo]

There is an issue on runbot now.