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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)

...

debug_docker_java_port = '-p {p}:{p}'.format(p=Util.debug_java_port) if Util.debug_java_port else ''
        docker_cmd = self._docker_cmd()
        docker_image = Util.docker_image_for_runtime(runtime)
        rm_flag = Util.get_docker_remove_flag()
        if config.LAMBDA_REMOTE_DOCKER:
            cmd = (
                'CONTAINER_ID="$(%s create -i'
                ' %s'  
                ' %s'  
                ' %s'  
                ' %s'  
                ' %s'  
                ' %s %s'  
                ')";'
                '%s cp "%s/." "$CONTAINER_ID:/var/task"; '
                '%s start -ai "$CONTAINER_ID";'
            ) % (docker_cmd, entrypoint, debug_docker_java_port, env_vars_string, network_str, rm_flag,
                 docker_image, command,
                 docker_cmd, lambda_cwd,
                 docker_cmd)
        else:
            lambda_cwd_on_host = Util.get_host_path_for_path_in_docker(lambda_cwd)
            cmd = (
                '%s run -i'
                ' %s -v "%s":/var/task'
                ' %s'
                ' %s'  
                ' %s'  
                ' %s %s'
            ) % (docker_cmd, entrypoint, lambda_cwd_on_host, env_vars_string,