[FIX] hr_holidays: fix no id to export when selecting all in tree view

Reproduce the issue

    - Install Time Off
    - Select all the lines
    - Action > Export

    The file has only columns but no data

Cause

    In `hr_leave_type.py` the `_search` method's limit is `False` when
    we select all the lines.

    In 04e85ef, we return the leaves ids with `[:limit]` so `[:False]`
    that always returns an empty array instead of `[:None]` that returns
    the full list.

This commit replaces the `[:limit]` by `[:limit or None]`

OPW-2126109

closes odoo/odoo#40622

X-original-commit: 2c0b58c161dff4fe9a8f953463ed2b1efdf7b431
Signed-off-by: Jason Van Malder <jasonvanmalder@users.noreply.github.com>

addons/hr_holidays/models/hr_leave_type.py

@@ -330,7 +330,7 @@ class HolidaysType(models.Model):
         leave_ids = super(HolidaysType, self)._search(args, offset=offset, limit=(None if post_sort else limit), order=order, count=count, access_rights_uid=access_rights_uid)
         leaves = self.browse(leave_ids)
         if post_sort:
-            return leaves.sorted(key=self._model_sorting_key, reverse=True).ids[:limit]
+            return leaves.sorted(key=self._model_sorting_key, reverse=True).ids[:limit or None]
         return leave_ids
 
     def action_see_days_allocated(self):