[XPU] bug fix block attn in mix mtp

[cmcamdy]

Motivation

测试开了MTP的benchmark时发现高batch下模型输出出现乱码，定位原因发现是split_rope_cache_kv_encoder没有在集中式场景下对qkv做偏移。

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Modifications

考虑集中式encoder decoder同时存在的情况，修复block attn

Usage or Command

Accuracy Tests

Checklist

• Add at least a tag in the PR title.
  • Tag list: [[FDConfig],[APIServer],[Engine], [Scheduler], [PD Disaggregation], [Executor], [Graph Optimization], [Speculative Decoding], [RL], [Models], [Quantization], [Loader], [OP], [KVCache], [DataProcessor], [BugFix], [Docs], [CI], [Optimization], [Feature], [Benchmark], [Others], [XPU], [HPU], [GCU], [DCU], [Iluvatar], [Metax]]
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• Add unit tests. Please write the reason in this PR if no unit tests.
• Provide accuracy results.
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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
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Additional details and impacted files

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[hong19860320]

LGTM