### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

When starting the transcription job in response job object is null:

<img width="1154" alt="Screenshot 2023-04-03 at 09 21 09" src="https://user-images.githubusercontent.com/454412/229447066-1671f811-da49-478d-bf24-252f30b17699.png">


### Expected Behavior

Response from the real AWS stack - job object is not null

<img width="1161" alt="Screenshot 2023-04-03 at 09 30 13" src="https://user-images.githubusercontent.com/454412/229441498-06125248-3b68-4679-8204-0163e8245db6.png">


### How are you starting LocalStack?

Custom (please describe below)

### Steps To Reproduce

Using test containers, reproducing project can be found here:

https://github.com/kkocel/local-stack-transcribe-repro

### Environment

```markdown
- OS: macOS
- LocalStack: latest
```


### Anything else?

_No response_
SUPPORTED_FORMAT_NAMES = {
    "amr": MediaFormat.amr,
    "flac": MediaFormat.flac,
    "mp3": MediaFormat.mp3,
    "mov,mp4,m4a,3gp,3g2,mj2": MediaFormat.mp4,
    "ogg": MediaFormat.ogg,
    "matroska,webm": MediaFormat.webm,
    "wav": MediaFormat.wav,
}
os.environ["VOSK_MODEL_PATH"] = str(LANGUAGE_MODEL_DIR)
from vosk import MODEL_PRE_URL, KaldiRecognizer, Model, SetLogLevel  
SetLogLevel(-1)
_DL_LOCK = threading.Lock()
class TranscribeProvider(TranscribeApi, ServiceLifecycleHook):
    def on_before_start(self):
        ffmpeg_package.install()
    #
    
    #
    def get_transcription_job(
        self, context: RequestContext, transcription_job_name: TranscriptionJobName
    ) -> GetTranscriptionJobResponse:
        store = transcribe_stores[context.account_id][context.region]
        if job := store.transcription_jobs.get(transcription_job_name):
            return GetTranscriptionJobResponse(TranscriptionJob=job)
        raise NotFoundException(
            "The requested job couldn't be found. Check the job name and try your request again."
        )
    @handler("StartTranscriptionJob", expand=False)
    def start_transcription_job(