Remove delete permissions for read-only federated reshares

An incomming federated share is just a mount point. Therefor if we
request the permissions on the mountpoint DELETE permissions will be
returned (among others). Since we can always remove a mountpoint, update
a mount point.

However now when trying to reshare we will try to reshare with DELETE
permissions. Which is false.

This PR removes the delete permissions if it is a shared storage.

Basically a quick hack.
Fixes #22587