Completely remove the py_clif_cc(gen_pybind11) option.

This is to simplify the work under b/309880216, in particular cl/581644444.

The option is not being used outside third_party/clif and devtools/clif.

PiperOrigin-RevId: 582748463

clif/python/primer.md

@@ -4,8 +4,6 @@ This is a user guide for using Python CLIF - The Python extension module
 generator that wraps C++ libraries.
 It tries to be clear and explain all the nuances involved in detail.
 
-.
-
 The organization of this document is such that it starts with illustration of
 the simplest of CLIF wrappings and progressively builds on this information
 in the following sections. Hence, if you are new to CLIF, read these sections in