[FIX] stock: improve performance of `report.stock.quantity`

Use UNION ALL instead of UNION to let PostgreSQL
filter out rows before sorting and avoid Unique check.
Note that it shouldn't change the result because each 3 SELECT
doesn't have domain intersection.

Improve performance the `_get_orderpoint_action` and the Forecasted
Inventory.

Performance Gain:
With a large Database (5K products, 120K stock move, 20K quants, etc):
To open the Forecasted Inventory:
Before: 10.06 sec +- 0.02
After:   3.98 sec +- 0.07

task-2390516

0 files changed, 0 insertions, 0 deletions