Steps to reproduce:
- Go to a project
- Open the task list view
- Select a task
- In the `Stage` field, attempt to create a new stage

Issue:
- Project users were able to create new task stages from the task list view, despite not having the required permissions.

Cause:
- The `_default_user_id` method assigns the current user as the owner `user_id` of a new stage only when `default_project_id` is not present in the context. As a result, the method returned the current user’s ID, unintentionally making them the owner of the stage. This allowed project users to bypass the intended access rules and create new stages.

Solution:
- Use the `no_create` option for users outside the project manager group to prevent them from creating new stages.
- Updated the `stage_id` field in the task list view to explicitly include `default_project_id` in the context, ensuring proper access control of that stage.

task-4628666

---
I confirm I have signed the CLA and read the PR guidelines at www.odoo.com/submit-pr

Forward-Port-Of: odoo/odoo#206407