Describe the bug

For the valid cases, TCGC reports wrong diagnostics "conflicting-multipart-model-usage"

Reproduction

    @service({title: "Test Service"}) namespace TestService;

    model MultiPartRequest {
      id: string;
      profileImage: bytes;
    }
    
    @post op basic1(@header contentType: "multipart/form-data", @body body: MultiPartRequest): NoContentResponse;
    @put op basic2(@header contentType: "multipart/form-data", @body body: MultiPartRequest): NoContentResponse;

Checklist

• Follow our Code of Conduct
• Check that this issue is about the Azure libraries for typespec. For bug in the typespec language or core libraries file it in the TypeSpec repo
• Check that there isn't already an issue that request the same bug to avoid creating a duplicate.
• The provided reproduction is a minimal reproducible example of the bug.