OCM. federated connection is not dropped when one of the users deletes the connection

```
Web UI 10.3.0
Ocis: 6.5.0
```

Steps:
`Given using server "LOCAL"`
`And "Alice" has generated invitation`
`And using server "REMOTE"`
`And "Brian" has accepted invitation`
`And using server "LOCAL"`
`When "Alice" deletes federation connection with user "Brian"`

Actual:
Alice cannot longer find and share to Brian - correct
but Brian can find and share to Alice

Expected: both users cannot find and share with each other

Start by reproducing the listed LOCAL/REMOTE federation scenario on the stated Web UI and ocis versions, focusing on connection deletion and file-sharing visibility. Done means that after Alice deletes the connection, Brian also cannot find or share with Alice; the payload does not name a source file or test.

Written by the indexing model from the issue text.