[FIX] hr_holidays: fasten creation of leaves by company
[FIX] hr_holidays: fasten creation of leaves by company

When creating a leave, we usually check/create activities for the
concerned users, this is fine when creating one leave.
However it starts to become a problem when trying to create leaves in
batch using the by company or by department holiday_type as the number
of leaves created in batch can become quite big.

Now when we create leaves in batch, we do not check for the activities,
which will fasten a lot the creation.

Another problem is that when someone defined a leave on the very day you
want to create such a request, then it will crash, this can lead to
waste of time and resources.

Now we raise an error before trying to create the leaves in case of
conflict.

Task: 1934383

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo