[NIXL] Fix blocksize=128 after hetero block size PR

[xuechendi]

Purpose

quick fix when block_size=128, need to update physical_block_size to self.kv_topo

Test Plan

Test Result

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Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
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[gemini-code-assist]

Code Review

This pull request addresses a critical bug in the NIXL connector related to heterogeneous block sizes. When the logical block size from the configuration differs from the physical block size required by the attention kernel, the worker's block_size attribute is updated. However, the original code failed to propagate this update to the kv_topo.block_size and _block_size attributes, which would lead to inconsistent state and incorrect calculations for KV cache transfers. The change correctly synchronizes these attributes, ensuring the integrity of the heterogeneous block size logic. The fix is well-targeted and necessary for the correct functioning of the NIXL connector in such scenarios.

[xuechendi]

@NickLucche , need help for quick review for fixing block_size=128 after supporting heter block size.
Will need to set physical block size in self.kv_topo