### Summary

The units in `test/units/plugins/strategy/test_strategy.py` have become problematic, and fail randomly due to something in the test not properly tearing down ansible.  Eventually the tests are killed in CI, and most frequently on python3.5.

See https://github.com/ansible/ansible/pull/74048

### Issue Type

Bug Report

### Component Name

test/units/plugins/strategy/test_strategy.py

### Ansible Version

```console (paste below)
$ ansible --version
2.11
```


### Configuration

```console (paste below)
$ ansible-config dump --only-changed

```


### OS / Environment

default test container, frequently with Py3.5 in CI

### Steps to Reproduce

<!--- Paste example playbooks or commands between quotes below -->
```yaml (paste below)

```


### Expected Results

No hang in CI

### Actual Results

Transient hangs in CI

if group_name in ('all', 'foo'):
                return mock_group
            return None
        mock_inventory = MagicMock()
        mock_inventory._hosts_cache = dict()
        mock_inventory.hosts.return_value = mock_host
        mock_inventory.get_host.side_effect = _get_host
        mock_inventory.get_group.side_effect = _get_group
        mock_inventory.clear_pattern_cache.return_value = None
        mock_inventory.get_host_vars.return_value = {}
        mock_inventory.hosts.get.return_value = mock_host
        mock_var_mgr = MagicMock()
        mock_var_mgr.set_host_variable.return_value = None
        mock_var_mgr.set_host_facts.return_value = None
        mock_var_mgr.get_vars.return_value = dict()
        strategy_base = StrategyBase(tqm=mock_tqm)
        strategy_base._inventory = mock_inventory
        strategy_base._variable_manager = mock_var_mgr
        strategy_base._blocked_hosts = dict()
        def _has_dead_workers():
            return False
        strategy_base._tqm.has_dead_workers.side_effect = _has_dead_workers
        results = strategy_base._wait_on_pending_results(iterator=mock_iterator)
        self.assertEqual(len(results), 0)
        task_result = TaskResult(host=mock_host.name, task=mock_task._uuid, return_data=dict(changed=True))
        queue_items.append(task_result)
        strategy_base._blocked_hosts['test01'] = True
        strategy_base._pending_results = 1
        def mock_queued_task_cache():