fix(event_handler): omit Content-Type header from OpenAPI

[DebadityaHait]

Issue number: Fixes #8347

Summary

Changes

• omit the Content-Type header parameter from generated OpenAPI operations
• keep Content-Type header fields in the runtime validation path
• cover direct and Pydantic-model header declarations

User experience

Before, a route that used Body(media_type=application/json-patch+json) and a Literal[...] Content-Type header emitted both the correct request-body media type and a redundant in: header content-type parameter.

After, the request-body media type remains in requestBody.content, content-type is omitted from the generated parameter list, and runtime validation still returns 422 for an incorrect media type.

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[boring-cyborg]

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.64%. Comparing base (ad15c7a) to head (c88a5a3).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #8374   +/-   ##
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  Coverage    96.64%   96.64%           
========================================
  Files          296      296           
  Lines        14764    14765    +1     
  Branches      1245     1245           
========================================
+ Hits         14268    14269    +1     
  Misses         361      361           
  Partials       135      135           

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[leandrodamascena]

Thanks for working on this @DebadityaHait

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[boring-cyborg]

Awesome work, congrats on your first merged pull request and thank you for helping improve everyone's experience!

[powertools-for-aws-oss-automation]

Awesome work, congrats on your first merged pull request and thank you for helping improve everyone's experience!