repl: remove deprecated repl.turnOffEditorMode() function

This function is deprecated for multiple years and provides very
little benefit to users. Thus, it's removed to improve the
maintainability of the REPL module.

Signed-off-by: Ruben Bridgewater <ruben@bridgewater.de>

PR-URL: https://github.com/nodejs/node/pull/33286


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>