Update Ballista to use new physical plan formatter utility

[andygrove]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
Ballista contains some hacky code for formatting physical query plans and we can now remove this and use the new physical plan formatting code that was recently added to DataFusion.

Describe the solution you'd like
Use the new displayable method.

Describe alternatives you've considered
None

Additional context
None