pd.Series.to_string(index=False) behavior changed to include leading spaces
This is a change in behavior between 0.23 and 0.25.

On `0.23.0`
```
In [10]: s=pd.Series(['a','b','c'])
       : s.to_string(index=False)
Out[10]: 'a\nb\nc'
```
On `0.25.0`
```
In [2]: s=pd.Series(['a','b','c'])
      : s.to_string(index=False)
Out[2]: ' a\n b\n c'
```
Particularly strange with a series of length 1
```
In [8]: s=pd.Series(['a'])
      : s.to_string(index=False)
Out[8]: ' a'
```

There is always exactly 1 leading space regardless of how many characters the index would have taken.  The same behavior appears in `DataFrame.to_string`.

Is this an intended change in behavior?  I'm happy to look into identifying the cause if it is not intended.