Change Manila cephfs driver

Currently used cephfs driver have been deprecated in Pike [1], change to use
the proper one.

[1]: https://opendev.org/openstack/manila/src/branch/master/releasenotes/notes/rename-cephfs-native-driver-3d9b4e3c6c78ee98.yaml

Closes-Bug: #1858773
Change-Id: I33bea1d0049accd48c61f85c1165bee1e1cf0c87