BUG: Don't print stray newline with MultiIndex
Title is self-explanatory.

Closes #6618.

## [Current coverage](https://codecov.io/gh/pydata/pandas/pull/14132?src=pr) is 85.27% (diff: 100%)

> Merging [#14132](https://codecov.io/gh/pydata/pandas/pull/14132?src=pr) into [master](https://codecov.io/gh/pydata/pandas/branch/master?src=pr) will decrease coverage by **<.01%**

``` diff
@@             master     #14132   diff @@
==========================================
  Files           139        139          
  Lines         50553      50554     +1   
  Methods           0          0          
  Messages          0          0          
  Branches          0          0          
==========================================
  Hits          43110      43110          
- Misses         7443       7444     +1   
  Partials          0          0          
```

> Powered by [Codecov](https://codecov.io?src=pr). Last update [58199c5...d1a600f](https://codecov.io/gh/pydata/pandas/compare/58199c5da263491a26fa6cb26d2ff9d38c4b5dac...d1a600f5fbc25a732ce8859db7e59d2936f49c8d?src=pr)
 thanks!
