Remove internal logic to handle bytecode version 3 (#57775)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/57775
The minimum supported bytecode version is updated from 3 to 4. We no longer support version 3 bytecode models.
Why?
* There are hacky codes in operator loading, that performs differently on one operator on the global bytecode version 3. Instead operator related metadata should be passed (for example, in #56845). To allow future development, we remove the hacky way first.
* The bytecode version was bumped from 3 to 4 more than half a year ago. Since all the production models are all bumped to version 4, it's not practical to keep and maintain version 3. The risk to deprecate version 3 is low.
Test Plan: Imported from OSS
Reviewed By: raziel
Differential Revision: D28270791
Pulled By: cccclai
fbshipit-source-id: 70b1bd6352fdaae5f8d2173b81578d77018c8e44
(cherry picked from commit 3e930fa381cd01f3705116795c6426df992372fc)
