### 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_
store, job_name = args
        job = store.transcription_jobs[job_name]
        job["StartTime"] = datetime.datetime.utcnow()
        job["TranscriptionJobStatus"] = TranscriptionJobStatus.IN_PROGRESS
        failure_reason = None
        try:
            LOG.debug("Starting transcription: %s", job_name)
            
            file_path = new_tmp_file()
            s3_client = aws_stack.connect_to_service("s3")
            s3_path = job["Media"]["MediaFileUri"]
            bucket, _, key = s3_path.removeprefix("s3://").partition("/")
            s3_client.download_file(Bucket=bucket, Key=key, Filename=file_path)
            ffmpeg_bin = ffmpeg_package.get_installer().get_ffmpeg_path()
            ffprobe_bin = ffmpeg_package.get_installer().get_ffprobe_path()
            LOG.debug("Determining media format")
            
            ffprobe_output = json.loads(