[Optimize] Unlimit max batch size

[rainyfly]

Motivation

由于 engine将生成的 token 返回到服务层采用 ipc msg queue 通信，需要提前创建缓存区大小。
缓冲区的大小由服务预设的能支持的最大max batch size 决定，max_num_seqs 不能大于创建缓冲区时候使用的 max batch size 大小。
之前512 的设置在部分场景已经不满足需求，在改变 engine 和服务层 token 传递的通信方式之前，将创建缓冲区的 max batch size 改为 2048。

Modifications

服务最大 max batch size 支持到 2048

Usage or Command

None

Accuracy Tests

None

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]]
  • You can add new tags based on the PR content, but the semantics must be clear.
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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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[paddle-bot]

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