Merge pyodide_py into python_stdlib.zip. ### Description

Merges pyodide_py.tar into python_stdlib.zip. This reduces the number of network requests during the initialization.

The original intention of splitting pyodide_py.tar from pyodide.asm.data was to give users an option to provide custom files (#2023), which is now available by modifying python_stdlib.zip directly. So I think there is no reason to have both python_stdlib.zip and pyodide_py.tar.

### Checklists

- [x] Add a [CHANGELOG](https://github.com/pyodide/pyodide/blob/main/docs/project/changelog.md) entry
- [x] Add / update tests

package:
  name: threadpoolctl
  version: 3.1.0
  top-level:
    - threadpoolctl
source:
  url: https://files.pythonhosted.org/packages/61/cf/6e354304bcb9c6413c4e02a747b600061c21d38ba51e7e544ac7bc66aecc/threadpoolctl-3.1.0-py3-none-any.whl
  sha256: 8b99adda265feb6773280df41eece7b2e6561b772d21ffd52e372f999024907b
about:
  home: https://github.com/joblib/threadpoolctl
  PyPI: https://pypi.org/project/threadpoolctl
  summary: threadpoolctl
  license: BSD-3-Clause

package:
  name: threadpoolctl
  version: 3.1.0
  top-level:
    - threadpoolctl
source:
  url: https://files.pythonhosted.org/packages/61/cf/6e354304bcb9c6413c4e02a747b600061c21d38ba51e7e544ac7bc66aecc/threadpoolctl-3.1.0-py3-none-any.whl
  sha256: 8b99adda265feb6773280df41eece7b2e6561b772d21ffd52e372f999024907b
about:
  home: https://github.com/joblib/threadpoolctl
  PyPI: https://pypi.org/project/threadpoolctl
  summary: threadpoolctl
  license: BSD-3-Clause
