Leading space in to_string(index=False)
#11750

``` python
In [2]: df = pd.DataFrame({'a':range(5)})

In [3]: df.to_string()
Out[3]: '   a\n0  0\n1  1\n2  2\n3  3\n4  4'

In [4]: df.to_string(index=False)
Out[4]: ' a\n 0\n 1\n 2\n 3\n 4'
```

What is the use of a leading space when index = False ?
