hotfix: fix the the threshold check logic of WriteBinaryNocopy

[YangruiEmma]

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en:
Kitex v0.11.0 has added a dependency on github.com/cloudwego/gopkg, and the thrift encoding logic has also been migrated to github.com/cloudwego/gopkg. However, the migrated code introduces a bug in the modification of WriteBinaryNocopy, resulting in all string/[]byte encodings executing WriteDirect after the total package exceeds 4k, leading to performance degradation. #20 has been fixed.
Trigger scenario: Data package>4k, with many encoding logics for small strings
Impact point: CPU increases and has a significant impact on latency

zh(optional):
kitex v0.11.0 新增 github.com/cloudwego/gopkg 依赖，同时 thrift 编码逻辑也迁移至 github.com/cloudwego/gopkg，但迁移后的代码对 WriteBinaryNocopy 的修改引入了 bug，导致数据总包超过 4k 后，所有字符串/[]byte编码都会执行 WriteDirect，进而导致性能劣化。#20 已经修复。
触发场景：数据总包 > 4k，有很多小字符串的编码逻辑
影响点：CPU 上升且对延迟有显著影响

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