Disable the toco binary in pip feature until it can used shared libs (#18061)

* Disable the toco binary in pip feature until it can used shared libraries.

The binary size was doubled by the saved model change. Since to process
saved models most of the TensorFlow runtime is needed. A workaround to
this is in the works and should be submitted in the next couple weeks.

* Fix linter errors with unused tensorflow libs

* Mollify the linter by removing os.