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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)

...

import os
import json
import time
import unittest
import requests
from botocore.exceptions import ClientError
from localstack.utils import testutil
from localstack.utils.testutil import get_lambda_log_events, get_lambda_log_group_name
from localstack.utils.aws import aws_stack
from localstack.utils.common import short_uid, retry, to_str
from .lambdas import lambda_integration
from .test_lambda import TEST_LAMBDA_PYTHON, LAMBDA_RUNTIME_PYTHON36, TEST_LAMBDA_LIBS
TEST_QUEUE_NAME = 'TestQueue'
TEST_POLICY = """
{
  "Version":"2012-10-17",