### 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.
Bucket=s3_bucket, Key=_key, ExpiresIn=60
        )
        # modi
        original_policy = presigned_request["fields"]["policy"]
        presigned_request["fields"]["policy"] = original_policy[:-2]
        response = .post(
            presigned_request["url"],
            data=presigned_request["fields"],
            files={"file": "file content"},
            verify=False,
        )
        # the 
        exception = xmltodict.parse(response.content)
        exception["StatusCode"] = response.status_code
        snapshot.match("exception-policy", exception)
        # asse
        signature_field = "signature" if signature_version == "s3" else "x-amz-signature"
        assert (
            exception["Error"]["SignatureProvided"] == presigned_request["fields"][signature_field]
        )
        assert exception["Error"]["StringToSign"] == presigned_request["fields"]["policy"]
    @pytest.mark.aws_validated
    @pytest.mark.xfail(
        condition=LEGACY_S3_PROVIDER, reason="Signature is not validated in legacy provider"
    )
    @pytest.mark.parametrize(
        "signature_version",
        ["s3", "s3v4"],
    )
    def test_post_request_missing_signature(