optimize _update_per_bucket_p2p logic

[specture724]

Resolve #25
Merge _update_per_bucket_p2p with _update_per_bucket. Topology-awared receiver assignment strategy implemented to make full use of bandwidth

[Copilot]

Pull Request Overview

This PR optimizes the P2P (peer-to-peer) update logic by merging the _update_per_bucket_p2p function with the existing _update_per_bucket function and implementing a topology-aware receiver assignment strategy to maximize bandwidth utilization.

• Consolidated P2P and broadcast update logic into a single unified function
• Added RDMA device topology awareness for optimal receiver assignment
• Enhanced metadata structures to include RDMA device information

Comments suppressed due to low confidence (1)

checkpoint_engine/ps.py:1

• This line was removed but self._current_global_parameter_metas is still being used later in the function without proper initialization. This could cause issues if the dictionary is not properly initialized elsewhere.

from __future__ import annotations

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