[lib] Remove message spec code for deprecated codeVersions

Summary: See recent comments in ENG-3625

Test Plan:

1. I confirmed that the code that uses shimUnsupportedMessageInfo in message-utils.js simply uses the rawMessageInfo if no shimUnsupportedMessageInfo is defined
2. Flow

Reviewers: tomek, michal, kamil

Reviewed By: tomek

Subscribers: wyilio

Differential Revision: https://phab.comm.dev/D9428