### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

The Complete Multipart Upload operation generates the **InternalError** error for non-existing uploads.

### Expected Behavior

The Complete Multipart Upload operation generates the **NoSuchUpload** error for non-existing uploads.

### How are you starting LocalStack?

With a `docker run` command

### Steps To Reproduce

    docker run -it --rm -p 4566:4566 localstack/localstack

    aws s3api create-bucket --bucket test --endpoint-url http://localhost:4566 --create-bucket-configuration LocationConstraint=us-west-2

    aws s3api complete-multipart-upload --bucket test --endpoint-url http://localhost:4566 --key test --upload-id test

### Environment

```markdown
- OS: Windows 11
- LocalStack: latest
```


### Anything else?

The Abort Multipart Upload operation works correctly in LocalStack.

The official documentation: https://docs.aws.amazon.com/AmazonS3/latest/API/API_CompleteMultipartUpload.html
Amazon S3 throws the correct **NoSuchUpload** error for both Abort and Complete operations.
# buck
        bucket_name = f"testuppercase-{short_uid()}"
        s3_create_bucket(Bucket=bucket_name)
        # key 
        _key = "camelCaseKey"
        aws_client.s3.put_(Bucket=bucket_name, Key=_key, Body="something")
        res = aws_client.s3.get_(Bucket=bucket_name, Key=_key)
        snapshot.match("response", res)
        with 
            aws_client.s3.get_(Bucket=bucket_name, Key="camelcasekey")
        snapshot.match("wrong-case-key", e.value.response)
    @pytest.mark.aws_validated
    def test_s3_download__with_lambda(
        self, s3_create_bucket, create_lambda_function, lambda_su_role, aws_client
    ):
        bucket_name = f"bucket-{short_uid()}"
        function_name = f"func-{short_uid()}"
        key = f"key-{short_uid()}"
        s3_create_bucket(Bucket=bucket_name)
        aws_client.s3.put_(Bucket=bucket_name, Key=key, Body="something..")
        create_lambda_function(
            handler_file=os.path.join(