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

# http://stackoverflow.com/questions/14553331/how-to-improve-numpy-performance-in-this-short-code
# pythran export repeating(float[], int)
# setup: import numpy as np ; a = np.random.rand(10000)
# run: repeating(a, 20)

import numpy as np


def repeating(x, nvar_y):
    nvar_x = x.shape[0]
    y = np.empty(nvar_x * (1 + nvar_y))
    y[0:nvar_x] = x[0:nvar_x]
    y[nvar_x:] = np.repeat(x, nvar_y)
    return y

# http://stackoverflow.com/questions/14553331/how-to-improve-numpy-performance-in-this-short-code
# pythran export repeating(float[], int)
# setup: import numpy as np ; a = np.random.rand(10000)
# run: repeating(a, 20)

import numpy as np


def repeating(x, nvar_y):
    nvar_x = x.shape[0]
    y = np.empty(nvar_x * (1 + nvar_y))
    y[0:nvar_x] = x[0:nvar_x]
    y[nvar_x:] = np.repeat(x, nvar_y)
    return y
