CLN: remove unnecessary to_dense call
This call is not reached in the tests, and if it were the following line would make it superfluous anyway.

I'm pretty sure the comment there is wrong too.
> This call is not reached in the tests

CategoricalArray and SparseArray have a to_dense methods and therefore hasattr(values, "to_dense") would be True.

However, `format_array` would use ExtensionArrayFormatter and not FloatArrayFormatter for these so hasattr(values, "to_dense") should always be False in FloatArrayFormatter.

ExtensionArrayFormatter dispatches back to format_array with a numpy array.  Thanks @jbrockmendel 