* converts dynamic domain from onchange_department_or_employee_id to a
static domain on the field
* remove the department_id field (and all uses of it), it looks to
never be set and not really be settable: the field is hidden in the
form, doesn't have a default value, does not have anything to
compute it, ...
* remove the onchange itself as it has very little value: it
auto-selects an equipment if there exists a single equipment
assigned to the selected employee or to no employee
Even if we removed the "equipment not assigned to any user"
bit (under the assumption that people would mostly request
maintenance for their own equipment, and that this would usefully
trigger more often) it's unlikely for dedicated users of
hr_maintenance to assign only one equipment per employee. So the
onchange would rarely do any useful work, and what work it saves is
trivial: if there's only one equipment the employee could ask about
for maintenance it's really trivial to do that.
Task 2115472
closesodoo/odoo#40963
Signed-off-by: Xavier Morel (xmo) <xmo@odoo.com>