We have some tests that check if receiving a forwarded room key works.
These claim to use the same user id, but in fact they change the user id
in the last moment before the event is passed into the client.

Let's change this so we're always operating with the same user id.

We never accept such room keys, so there isn't a point in requesting
them.

Co-authored-by: Richard van der Hoff <[email protected]>

…est-room-keys-from-other-users