fix(ttstream): ttstream should supplement sending Header Frame when exiting handler directly

[DMwangnima]

What type of PR is this?

fix

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• This PR title match the format: <type>(optional scope): <description>
• The description of this PR title is user-oriented and clear enough for others to understand.
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fix(ttstream): 当直接退出 handler 时，ttstream 应当补充发送 Header 帧

(Optional) More detailed description for this PR(en: English/zh: Chinese).

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根据 TTHeader Streaming 协议，一个 Stream 某个方向的第一个 Frame 应当是 Header Frame。
从 Kitex 支持 TTHeader Streaming 开始(v0.12.0)，当直接退出 handler 时，只会发送 Trailer Frame，不会补发 Header Frame

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[codecov]

Codecov Report

❌ Patch coverage is 42.85714% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 61.33%. Comparing base (bfa27f3) to head (256c170).
⚠️ Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/remote/trans/ttstream/stream_server.go	33.33%	1 Missing and 1 partial ⚠️
pkg/remote/trans/ttstream/test_utils.go	50.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1887      +/-   ##
==========================================
- Coverage   61.37%   61.33%   -0.05%     
==========================================
  Files         388      388              
  Lines       35063    29849    -5214     
==========================================
- Hits        21521    18307    -3214     
+ Misses      12247    10245    -2002     
- Partials     1295     1297       +2     

Flag	Coverage Δ
integration	51.84% <14.28%> (+1.33%)	⬆️
unit	51.61% <42.85%> (-0.04%)	⬇️

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