[FIX] project: project grouped by stages now respects the pagination
Steps to reproduce
==================
- Open any project
- Create many project stages (80+)
- Switch to the list view
- Group by stage
- Switch to to next page
=> The pager keeps increasing
Cause of the issue
==================
`stage_id` has a group_expand: `_read_group_stage_ids`
This method is used to include empty stages in the result for the kanban
view, so that we can drag tasks to an empty stage.
Solution
========
Add a context key `project_kanban` and only add empty stages in that
case.
opw-4408061
closes odoo/odoo#192955
X-original-commit: f4c41aa2836cd937cd476e50dcd494fc8549476a
Signed-off-by: Xavier Bol (xbo) <[email protected]>
