Bugfix: Update reva to v2.19.4

We updated reva to v2.19.4

*   Bugfix [cs3org/reva#4612](https://github.com/cs3org/reva/pull/4612): Use gateway selector in jsoncs3 to scale the service

https://github.com/owncloud/ocis/pull/8787

We updated reva to v2.19.3

*   Bugfix[cs3org/reva#4607](https://github.com/cs3org/reva/pull/4607): Mask user email in output

https://github.com/owncloud/ocis/pull/8781
