RendererServices::good() no longer used when generating textures

### Problem

While doing some texture work I noticed that the RendererServices::good() function is no longer being called when generating textures. The function serves as an interface to validate texture handles retrieved from RendererServices::get_texture_handle(). This was removed as of a5d8381afbe1ad3c16cd3db7f6e1ddf5c50e0b1f and the texture handle is now just checked if it is non NULL. What are the plans for this API moving forward? If it is no longer going to be used there should probably be some indication that it is deprecated.

### Versions

* OSL branch/version: master - 1.11.0
* OS: All
* C++ compiler: N/A
* LLVM version: N/A
* OIIO version: N/A

Start by tracing RendererServices::good() and the texture-handle generation path, then compare the current behavior with commit a5d8381afbe1ad3c16cd3db7f6e1ddf5c50e0b1f. Determine whether the API is still expected to validate handles and document the resulting behavior or deprecation status; the issue names no files or tests.

Written by the indexing model from the issue text.