[FIX] project: fix wrong subtask mapping while project copy

Steps to reproduce:
1. Install module Project
2. Enable Sub-Task feature in settings
3. Create a project A and add a task with subtasks with depth level >1.
4. Duplicate project A

Issue:
Duplicated child subtasks (depth >1) are not being mapped with the newly created project(duplicated one).

Cause:
Only mapping parent task due to wrong filter values.

Solution:
If the `display_project_id` of all tasks to duplicate (subtasks
included) are linked to the project to duplicate, then the
'display_project_id' of duplicated tasks for those tasks will be
the newly created project on all child subtasks record sets.

closes odoo/odoo#108875

Signed-off-by: Xavier Bol (xbo) <xbo@odoo.com>