[FIX] project: make tests demo data independent

The test `test_duplicate_project_duplicates_milestones_on_tasks` and the test class `TestSoLineMilestones`
fail when demo data are not installed.
This commit makes it demo data independent.

Task-3410352

closes odoo/odoo#128307

X-original-commit: 9193168d39a808d66e67ad8d5d704d72fdc5f3a0
Signed-off-by: Xavier Bol (xbo) <xbo@odoo.com>

addons/project/tests/test_project_milestone.py

@@ -61,7 +61,10 @@ class TestProjectMilestone(TestProjectCommon):
         unique_name_1 = "unique_name_1"
         unique_name_2 = "unique_name_2"
         unique_names = [unique_name_1, unique_name_2]
-        project = self.env['project.project'].create({'name': 'Test project'})
+        project = self.env['project.project'].create({
+            'name': 'Test project',
+            'allow_milestones': True,
+        })
         milestones = self.env['project.milestone'].create([{
             'name': unique_name_1,
             'project_id': project.id,

addons/sale_project/tests/test_so_line_milestones.py

@@ -14,6 +14,7 @@ class TestSoLineMilestones(TestSaleCommon):
     def setUpClass(cls, chart_template_ref=None):
         super().setUpClass(chart_template_ref=chart_template_ref)
 
+        cls.env['res.config.settings'].create({'group_project_milestone': True}).execute()
         uom_hour = cls.env.ref('uom.product_uom_hour')
 
         cls.product_delivery_milestones1 = cls.env['product.product'].create({