It seems that the `test_find_not_should_ignore_path` test has some dependency on side-effects from other tests. 

For example it failed here:

https://github.com/apache/airflow/pull/10983/checks?check_run_id=1127304894#step:6:1043

```
>       self.assertEqual(detected_files, should_not_ignore_files)
E       AssertionError: Items in the second set but not the first:
E       'test_load.py'
E       'test_load_sub1.py'
```

And re-running it in a clean system works just fine in the same combination of python/db.

**What you expected to happen**:

The test should clean up /restore everything it needs before running or a test that makes side-effects is found and fixed. 

For now I am moving the test to "heisentests with appropriate note.".

tests/plugins/test_plugin_ignore.py
"""
    Test that the .airflowignore work and whether the file is properly ignored.
    """
    def setUp(self):
        """
        Make tmp folder and files that should be ignored. And set base path.
        """
        self.test_dir = tempfile.mkdtemp()
        self.test_file = os.path.join(self.test_dir, 'test_file.txt')
        self.plugin_folder_path = os.path.join(self.test_dir, 'test_ignore')
        os.mkdir(os.path.join(self.test_dir, "test_ignore"))
        os.mkdir(os.path.join(self.plugin_folder_path, "subdir1"))
        os.mkdir(os.path.join(self.plugin_folder_path, "subdir2"))
        files_content = [
            ["test_load.py", "#Should not be ignored file"],
            ["test_notload.py", 'raise Exception("This file should have been ignored!")'],
            [".airflowignore", "#ignore test\nnot\nsubdir2"],
            ["subdir1/.airflowignore", "#ignore test\nnone"],
            ["subdir1/test_load_sub1.py", "#Should not be ignored file"],
            ["test_notload_sub.py", 'raise Exception("This file should have been ignored!")'],
            ["subdir1/test_noneload_sub1.py", 'raise Exception("This file should have been ignored!")'],
            ["subdir2/test_shouldignore.py", 'raise Exception("This file should have been ignored!")'],
        ]
        for file_path, content in files_content:
            with open(os.path.join(self.plugin_folder_path, file_path), "w") as f:
                f.write(content)
        self.mock_plugins_folder = patch.object(
            settings, 'PLUGINS_FOLDER', return_value=self.plugin_folder_path
        )
    def tearDown(self):