Adding Transform All policy for queries incorrectly removes query parameters in the backendUrl

According to the policy [docs](https://github.com/openwhisk/apigateway/blob/develop/doc/policies.md#reqmapping), to transform all query parameters to body, you would put this in policies:
```
{
"action": "transform",
"from": {
"name": "*",
"location": "query"
},
"to": {
"name": "*",
"location": "body"
}
}
```
However, this also removes the query parameters in the backendUrl.

Start with the request-mapping policy documentation linked in the issue and reproduce the Transform All query-parameter case. Trace how query parameters are moved to the body and how backendUrl is formed; done means the parameters are transformed without being incorrectly removed from backendUrl.

Written by the indexing model from the issue text.