[BUG] [csharp-functions] Generator does not apply optionalEmitDefaultValues parameter

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

Running csharp-functions server generator generates model properties with [EmitDefaultValue=false)] attribute even though with passing optionalEmitDefaultValues=trueparameter. This is working with aspnetcore server generator but does not apply csharp-functions generator.

openapi-generator version

7.14.0

OpenAPI declaration file content or url

can be reproduced with the petstore file

Generation Details

openapi-generator-cli generate -i <file path> -g csharp-functions --additional-properties=optionalEmitDefaultValues=true

Steps to reproduce

run the command above

Related issues/PRs

This PR fixed the issue for aspnetcore generator but csharp-functions ramained buggy.
https://github.com/OpenAPITools/openapi-generator/pull/4010

Suggest a fix

Apply same fix from https://github.com/OpenAPITools/openapi-generator/pull/4010

Start with the csharp-functions generator and reproduce the issue using the petstore specification and the provided openapi-generator-cli command. Compare its handling of optionalEmitDefaultValues with the aspnetcore fix in PR 4010; done means the generated model properties reflect optionalEmitDefaultValues=true without the unwanted EmitDefaultValue=false attribute.