test(cohorts): make membership-count query assertion RBAC-agnostic

The private-package CI run installs RBAC, whose runtime role checks add
two permission queries, failing the hardcoded count of 10. Force
IS_RBAC_INSTALLED off for this test so the count is deterministic in
both variants; the test's subject is cohort membership counts staying
constant, not the permission stack.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: Zaimwa9

api/tests/unit/cohorts/test_views.py

@@ -31,7 +31,7 @@
 )
 
 if typing.TYPE_CHECKING:
-    from pytest_django.fixtures import DjangoAssertNumQueries
+    from pytest_django.fixtures import DjangoAssertNumQueries, SettingsWrapper
 
 
 def test_create_cohort__staff_with_manage_segments__returns_201(
@@ -177,8 +177,12 @@ def test_list_cohorts__multiple_cohorts__membership_counts_in_constant_queries(
     dynamodb_identity_wrapper: DynamoIdentityWrapper,
     with_environment_permissions: WithEnvironmentPermissionsCallable,
     django_assert_num_queries: "DjangoAssertNumQueries",
+    settings: "SettingsWrapper",
 ) -> None:
     # Given
+    # Keep the query count deterministic across OSS and private-package
+    # runs: RBAC's runtime role checks would add two permission queries.
+    settings.IS_RBAC_INSTALLED = False
     environment = edge_cohort.environment
     with_environment_permissions(  # type: ignore[call-arg]
         [VIEW_ENVIRONMENT], environment_id=environment.id