Remove obsolete tests and unused imports in organization members and management components

- Deleted `OrganizationMembersPage` tests as they are no longer relevant.
- Removed unused `updated_at` property from test data in multiple components.
- Cleaned up redundant `useAuth` imports from `OrganizationMembersContent` and `OrganizationManagementContent`.

frontend/tests/components/admin/organizations/OrganizationFormDialog.test.tsx

@@ -42,7 +42,6 @@ describe('OrganizationFormDialog', () => {
     description: 'Test description',
     is_active: true,
     created_at: '2025-01-01',
-    updated_at: '2025-01-01',
     member_count: 5,
   };