gh-127638: Prevent copying extended attributes of script files when creating venv

[wimglenn]

Prevent the regression in Python 3.13 on Linux when creating a venv from interpreter hosted on large xattr filesystem.

There are a few other copy2 usages in venv/__init__.py but they are all gated by conditions on os.name == 'nt' so don't affect Linux.

Instead of handling the possible error from the copy (which looks like: shutil.copy2 -> copystat -> _copyattr -> os.setxattr -> OSError: [Errno 28] No space left on device) I've opted to just remove that conditional. I don't think we want to have attrs or not based on whether new_data == data, rather we want them always there or not regardless of file content.

• Issue: Cannot create venvs on small-xattr filesystems when CPython is installed somewhere with large xattrs (Regression from 3.12) #127638