Ceph » rgw

Hi,

Ceph xml for listMultipartUploads response is not compatible with s3

`ListMultipartUploadsResult.Prefix` should just be `Prefix` and
`CommonPrefixes.Prefix` should just be `Prefix`

```

<ListMultipartUploadsResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/&quot;>
<Bucket>tes-20200918t022453-pnmkqpyi7mkvr0x</Bucket>

<ListMultipartUploadsResult.Prefix>1/b</ListMultipartUploadsResult.Prefix>

<CommonPrefixes>
<CommonPrefixes.Prefix>1/bb/</CommonPrefixes.Prefix><CommonPrefixes.Prefix>1/bbb/</CommonPrefixes.Prefix>
</CommonPrefixes></ListMul
```

From AWS documentation - https://docs.aws.amazon.com/AmazonS3/latest/API/API_ListMultipartUploads.html

HTTP/1.1 200

<ListMultipartUploadsResult>
<Bucket>string</Bucket>
<KeyMarker>string</KeyMarker>
<UploadIdMarker>string</UploadIdMarker>
<NextKeyMarker>string</NextKeyMarker>
<Prefix>string</Prefix>
<Delimiter>string</Delimiter>
<NextUploadIdMarker>string</NextUploadIdMarker>
<MaxUploads>integer</MaxUploads>
<IsTruncated>boolean</IsTruncated>
<Upload>
<Initiated>timestamp</Initiated>
<Initiator>
<DisplayName>string</DisplayName>
<ID>string</ID>
</Initiator>
<Key>string</Key>
<Owner>
<DisplayName>string</DisplayName>
<ID>string</ID>
</Owner>
<StorageClass>string</StorageClass>
<UploadId>string</UploadId>
</Upload>
...
<CommonPrefixes>
<Prefix>string</Prefix>
</CommonPrefixes>
...
<EncodingType>string</EncodingType>
</ListMultipartUploadsResult>