[pruner] Make bias hook stateless (#61077)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/61077
Removing `BiasHook` class, using function instead.
ghstack-source-id: 132899223
Test Plan:
` buck test mode/dev-nosan //caffe2/test:ao -- TestBasePruner`
https://pxl.cl/1L7Tg
Reviewed By: z-a-f
Differential Revision: D29504119
fbshipit-source-id: 6dd9689d18b17ac64e8a461f466e2c9018bc530b
