overlook of https://github.com/odoo/odoo/pull/239717
### Before this commit:
Runbot was red on weekends, as there are no work intervals on weekends.

### After this commit:
Use Friday as a fallback on weekends. In addition, improve the test performance by mocking the total number of weeks of planning to 2 instead of 50 (before: 6s, after: 1s).

runbot-237575

---

Note: ran the test for the next 5 years, and it works :+1: 
```diff
diff --git a/addons/mrp/tests/test_bom.py b/addons/mrp/tests/test_bom.py
index 7acf19e89add..bfadc8e487c1 100644
--- a/addons/mrp/tests/test_bom.py
+++ b/addons/mrp/tests/test_bom.py
@@ -13,6 +13,7 @@ from odoo.tests.common import HttpCase, tagged, freeze_time
 from odoo.tools import float_compare, float_round, float_repr
 
 
+@tagged("-at_install", "post_install")
 @freeze_time(fields.Date.today())
 class TestBoM(TestMrpCommon):
 
@@ -963,6 +964,16 @@ class TestBoM(TestMrpCommon):
             self.assertEqual(report_values['lines']['operations_time'], 15.0)
             self.assertEqual(report_values['lines']['producible_qty'], 2)
 
+    def test_bom_report_planning_with_producible_qty_loop(self):
+        from datetime import date  # noqa: PLC0415
+        start, stop = date.today(), date.fromisoformat("2031-01-01")
+        with freeze_time(start) as frozen_date:
+            for i in range((stop - start).days):
+                print("date:", str(date.today()))
+                with self.subTest(str(date.today())):
+                    self.test_bom_report_planning_with_producible_qty()
+                    frozen_date.tick(timedelta(days=1))
+
     def test_21_bom_report_variant(self):
         """ Test a sub BoM process with multiple variants.
         BOM 1:
```