Bugfix: Use binary client for Attrs

EOS < 5.3 has a couple of bugs related to attributes:
* Attributes can only be removed as root or the owner, but over gRPC we cannot become root
* The recursive property is ignored on set attributes

For these two issues, we circumvent them by calling the binary client until we have deployed EOS 5.3

https://github.com/cs3org/reva/pull/5123