Remove code which is used for streaming process

Since we haven't made the streaming process part of Bigflow opensource, we should have removed all the code related to it. We've done most of the work, but there still is some code for streaming process remaining.
So, remove the useless code, and keep the code clean.

No files, tests, or entry points are named. Start by locating the remaining streaming-process code and tracing its references; remove only code that is unused outside streaming, then run the project's available build and test checks to confirm non-streaming functionality remains intact.

Written by the indexing model from the issue text.