OCM. Removing a federated share does not update the resource's share-types

[JammingBen]

Describe the bug

Removing a federated share does not update the resource's share-types.

Steps to reproduce

1. Share a file that has no shares and links with a federated user
2. Do a PROPFIND on the resource -> oc:share-types includes 0
3. Remove the federated share
4. Do a PROPFIND on the resource again -> oc:share-types still includes 0

Expected behavior

share-types should be empty.

Actual behavior

share-types still includes 0

[rhafer]

Looks as if we're not removing the ("fake") grant for OCM shares from the storage provider when we're deleting ocm shares. (https://github.com/cs3org/reva/blob/edge/internal/grpc/services/gateway/ocmshareprovider.go#L92)