Do not collapse multiline docstrings

[Glyphack]

This issue was brought up in the review.

The summary is currently we collapse multiline docstrings, which is not compatible with black:

For example:

class Test:
    
    """
    Black's `Preview.module_docstring_newlines`


    A code black to format
"""

Black formats this to

class Test:
    """
    Black's `Preview.module_docstring_newlines`


    A code black to format
    """

and Ruff formats it to

class Test:
    """
    Black's `Preview.module_docstring_newlines`


    A code black to format"""