[WEB-8068] refactor: drop unnecessary distinct() from module listing

Address Copilot review: the project-membership join is filtered to
request.user, and ProjectMember has a unique constraint on (project, member)
where deleted_at IS NULL, so the join yields at most one row per project and
cannot duplicate Module rows. distinct() was dead weight (and a planner cost
for large workspaces). Matches the reference WorkspaceStates/WorkspaceLabels
endpoints, which use no distinct().

Also drop the distinct-focused contract test: adding a *different* project
member never fans out the request.user-filtered join, so it would pass with or
without distinct() — misleading coverage.

Co-authored-by: Plane AI <noreply@plane.so>

apps/api/plane/app/views/workspace/module.py

@@ -110,7 +110,6 @@ class WorkspaceModulesEndpoint(BaseAPIView):
                 )
             )
             .order_by(self.kwargs.get("order_by", "-created_at"))
-            .distinct()
         )
 
         serializer = ModuleSerializer(modules, many=True).data

apps/api/plane/tests/contract/app/test_workspace_cycles_modules_project_scope_app.py

@@ -120,25 +120,3 @@ class TestWorkspaceCyclesModulesProjectScope:
         assert response.status_code == status.HTTP_200_OK
         ids = {str(row["id"]) for row in response.data}
         assert str(module.id) in ids, f"Expected module {module.id} in {response.data!r}"
-
-    @pytest.mark.django_db
-    def test_modules_not_duplicated_for_project_member(
-        self, session_client, workspace, project, module
-    ):
-        """The project-member join must not duplicate a module row (.distinct())."""
-        # Add a second active member to the project so the reverse
-        # project_projectmember join fans out to more than one row.
-        other = User.objects.create(
-            email=f"peer-{uuid4().hex[:8]}@plane.so",
-            username=f"peer_{uuid4().hex[:8]}",
-        )
-        other.set_password("test-password")
-        other.save()
-        ProjectMember.objects.create(
-            project=project, member=other, workspace=workspace, role=15
-        )
-
-        response = session_client.get(MODULES_URL.format(slug=workspace.slug))
-        assert response.status_code == status.HTTP_200_OK
-        module_rows = [row for row in response.data if str(row["id"]) == str(module.id)]
-        assert len(module_rows) == 1, f"Module row duplicated: {response.data!r}"