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# Type of request: This is a ...

[x] bug report
[ ] feature request

# Detailed description

In the `ReceiveMessageResult` of the SQS service, I saw this XML from localstack:

```
...
<MessageAttribute>
     <Name>encoding</Name>
    <Value>
        <DataType>String</DataType>
        <StringValue><![CDATA[gzip]]></StringValue>
    </Value>
</MessageAttribute>
...
```

The `<![CDATA[gzip]]>` is slightly different from AWS, which doesn't wrap the value in a `<!CDATA[[]]>` section. This shouldn't be a problem for XML parsers that accept both plain characters and CDATA sections for this element, but the XML parser I was using did not, which causes an error when running the code against localstack but not when running the code against AWS. There is obviously a bug in the XML parser as well, but I thought that I should at least post this here since it is different than what AWS SQS does.

## Expected behavior

MessageAttribute::Value elements should not be wrapped in `CDATA` sections.

## Actual behavior

MessageAttribute::Value elements all seem to be wrapped in `CDATA` sections.

# Steps to reproduce

Send a message to the SQS service which contains some custom message attributes, then make a ReceiveMessageRequest.

## Command used to start LocalStack

`docker run --env "SERVICES=sqs" localstack/localstack`

## Client code (AWS SDK code snippet, or sequence of "awslocal" commands)

...

r = s.get(url, stream=True, verify=verify_ssl)
    
    if r.status_code >= 400:
        raise Exception('Failed to download %s, response code %s' % (url, r.status_code))
    total = 0
    try:
        if not os.path.exists(os.path.dirname(path)):
            os.makedirs(os.path.dirname(path))
        LOG.debug('Starting download from %s to %s (%s bytes)' % (url, path, r.headers.get('content-length')))
        with open(path, 'wb') as f:
            for chunk in r.iter_content(DOWNLOAD_CHUNK_SIZE):
                total += len(chunk)
                if chunk:  
                    f.write(chunk)
                    LOG.debug('Writing %s bytes (total %s) to %s' % (len(chunk), total, path))
                else:
                    LOG.debug('Empty chunk %s (total %s) from %s' % (chunk, total, url))
            f.flush()
            os.fsync(f)
        if os.path.getsize(path) == 0:
            LOG.warning('Zero bytes downloaded from %s, retrying' % url)
            download(url, path, verify_ssl)
            return
        LOG.debug('Done downloading %s, response code %s, total bytes %d' % (url, r.status_code, total))
    finally:
        r.close()
        s.close()
def first_char_to_lower(s):
    return '%s%s' % (s[0].lower(), s[1:])
def is_number(s):