refactor: remove unnecessary 'client' fixture and update test durations (#4283)

* Remove unnecessary use of 'client' fixture in test_superuser

* Remove unnecessary use of 'usefixtures' decorator in test files

* Update test fixtures to improve test duration tracking

* Remove unnecessary 'client' fixture from test cases

src/backend/tests/unit/test_cli.py

@@ -25,7 +25,6 @@ def test_components_path(runner, default_settings, tmp_path):
     assert str(temp_dir) in settings_service.settings.components_path
 
 
-@pytest.mark.usefixtures("client")
 def test_superuser(runner):
     result = runner.invoke(app, ["superuser"], input="admin\nadmin\n")
     assert result.exit_code == 0, result.stdout