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

(packages-in-pyodide)=

# Packages built in Pyodide

This is the list of Python packages included with the current version of
Pyodide. These packages can be loaded with {js:func}`pyodide.loadPackage` or
{py:func}`micropip.install`. See {ref}`loading_packages` for information about
loading packages. Pure Python packages with wheels on PyPI can be loaded
directly from PyPI with {py:func}`micropip.install`.

```{eval-rst}
.. pyodide-package-list :: packages
```

(packages-in-pyodide)=

# Packages built in Pyodide

This is the list of Python packages included with the current version of
Pyodide. These packages can be loaded with {js:func}`pyodide.loadPackage` or
{py:func}`micropip.install`. See {ref}`loading_packages` for information about
loading packages. Pure Python packages with wheels on PyPI can be loaded
directly from PyPI with {py:func}`micropip.install`.

```{eval-rst}
.. pyodide-package-list :: packages
```
