test: fix strict positional parameter enforcement under pytest

[Capstan]

Description

This PR fixes a test suite configuration bug where strict positional parameter checking was silently bypassed when running the tests under pytest.

Problem

Historically, strict positional parameter checking was enabled during test setup by setting util.positional_parameters_enforcement = "EXCEPTION" inside a setup_package() hook inside tests/__init__.py.

However, modern test runs in this repository (including through nox sessions) run under pytest. Unlike the legacy nose test runner, pytest does not automatically execute package-level setup_package() hooks.

Because this hook was ignored:

1. positional_parameters_enforcement remained in its default warning-only state.
2. Tests specifically designed to assert strict positional parameter failures (which expect TypeErrors to be thrown) were being bypassed or would fail if executed directly.

Solution

1. Moved the setting of util.positional_parameters_enforcement = "EXCEPTION" to the module level of tests/__init__.py. This ensures that the strict check environment is correctly initialized the moment pytest imports the tests package.
2. Completely removed the dead nose-legacy setup_package() hook to keep the codebase clean and free of deprecated test runner baggage.

Verification

Ran the strict positional test case directly using pytest on a clean virtual environment:

pytest tests/test_discovery.py -k test_tests_should_be_run_with_strict_positional_enforcement

• Before fix: Test failed with AssertionError (only warning log generated, no exception thrown).
• After fix: Test successfully passes (raises expected TypeError and asserts it correctly).

Fixes #2755

[gemini-code-assist]

Code Review

This pull request simplifies the test initialization in tests/__init__.py by removing the setup_package function and executing the configuration directly at the module level. The review feedback suggests using a predefined constant instead of a hardcoded string to prevent typos and improve maintainability.