💾 Integrate CephFS in CI

[tbsbdr]

v1 - before starting to deploy to staging/test system of customer

• setup CEPH cluster
• smoke test: manual testing

v2 - needs to happen after v1, but before production phase.

• needs to be integrated into our CI
• Documentation
  • Definition of done: CX Team says that the docu is self sufficient (=no need to ask engingeering)

[tbsbdr]

relates to https://github.com/owncloud/ocis/issues/8857