Add legacy gen for MedicalTranscriptResultStream

[dagnir]

Description

MedicalTranscriptResultStream$TrancriptEvent was released with the existing code
generation scheme so it needs to be customized.

Motivation and Context

Testing

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• I have read the CONTRIBUTING document
• Local run of mvn install succeeds
• My code follows the code style of this project
• My change requires a change to the Javadoc documentation
• I have updated the Javadoc documentation accordingly
• I have read the README document
• I have added tests to cover my changes
• All new and existing tests passed
• A short description of the change has been added to the CHANGELOG
• My change is to implement 1.11 parity feature and I have updated LaunchChangelog

License

• I confirm that this pull request can be released under the Apache 2 license

[dagnir]

Diff for generated files: https://gist.github.com/dagnir/178f522516086cdd48366cff841aed73

[dagnir]

This is the only new evenstream that I could find:

rg -F '"eventstream"' services/
services/transcribestreaming/src/main/resources/codegen-resources/service-2.json
7:    "protocolSettings":{"h2":"eventstream"},
91:      "eventstream":true
324:      "eventstream":true
745:      "eventstream":true

services/kinesis/src/main/resources/codegen-resources/service-2.json
8:    "protocolSettings":{"h2":"eventstream"},
1946:      "eventstream":true

services/s3/src/main/resources/codegen-resources/service-2.json
8744:      "eventstream":true