Unused, should remove.

It was added 8 years ago, in #14523, but the Python world has moved away from using readline: IPython is using different libraries for terminal interaction now.

CC: @dimpase @tscrim

Component: interfaces

Author: Matthias Koeppe, Travis Scrimshaw

Branch/Commit: ed14848

Reviewer: Travis Scrimshaw, Matthias Koeppe

Issue created by migration from https://trac.sagemath.org/ticket/32073