[BUG] The remained to be fixed for LFU frequency bug

[jiashuy]

Describe the bug We solved the LFU bug for EmbeddingCollection's forward and backward. But has some remain works for EmbeddingBagCollection and Prefetch.

Steps/Code to reproduce bug

Expected behavior

• Fix the bug in EmbeddingBagCollection
• Fix the bug in prefetch(For prefetching, We don't need to update score for existed keys, but have to assign a score for new keys.And for LRU, its score is updated every time.)
• Remove erase API call, and fix the unexpected_score_accumulated issue in HKV.

Environment details (please complete the following information):

• Environment location: [Bare-metal, Docker, Cloud(specify cloud provider)]
• Method of recsys-examples install: [conda, Docker, pip, or from source]
  • If method of install is [Docker], provide docker pull & docker run commands used
• Run print_env.sh from the project root and paste the results here

Additional context Add any other context about the problem here.

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[z52527]

After adding the admission function, the problem of prefetch updating scores still exists. #111

[JacoCheung]

Continue working on this after counter table is done.