get rid of bundled init_cinderx (take #2)

Summary:
First attempt (D70263853) was reverted because it triggered stack overflows when
the Cinder interpreter loop loaded import cycles w/ Lazy Imports enabled. This is
fixed in D68841472.

**Below is copied from D70263853**

Instead of this, we'll just inject it into our builds similar to how we inject a dependency on `//cinderx:_cinderx`

Reviewed By: brittanyrey

Differential Revision: D71057292

fbshipit-source-id: f1cca6816d390367815413588a8a7bcf0f74e297

Author: Alex Malyshev