Issue #16424: List all providers when creating salt-cloud instance without profile

 `mapper.map_providers_parallel()` filters out providers that return empty data, saltify always return empty dictionaries, so it's never included into the output, therefore `cloud.CloudClient.create()` never works for saltify.

This PR replaces `mapper.map_providers_parallel()` call with just `self.opts['providers']` that is just as good for the purpose.