fix: adjust WebSocket buffer sizes in terminal and host API

[HynoR]

What this PR does / why we need it?

websocket 给 write 初始化分配10M buffer 太奢侈了，用不上还吃内存

Summary of your change

降低 writebuffersize到一个相对保守的值, 把 readzise 换成默认值 4096，终端功能可以依然正常行使功能

Please indicate you've done the following:

• Made sure tests are passing and test coverage is added if needed.
• Made sure commit message follow the rule of Conventional Commits specification.
• Considered the docs impact and opened a new docs issue or PR with docs changes if needed.

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