Don't register claim_keys and user_devices as queries

This issue has been migrated from [#3762](https://github.com/matrix-org/synapse/issues/3762).

---

This has caused me many hours of frustration in trying to figure out why the query endpoints don't work as they should.

They are both registered here:
https://github.com/matrix-org/synapse/blob/74854a97191191b08101821753c2672efc2a65fd/synapse/handlers/device.py#L52-L54
https://github.com/matrix-org/synapse/blob/d69decd5c78c72abef50b597a689e2bc55a39702/synapse/handlers/e2e_keys.py#L41-L46

They are then only ever invoked manually:
https://github.com/matrix-org/synapse/blob/74854a97191191b08101821753c2672efc2a65fd/synapse/federation/federation_server.py#L468-L473

The registration means that they are also bound to `/query/user_devices` and `/query/client_keys`, which feel like useful APIs to have, however they return 500 regardless of input.

Considering both of these work around the query handlers, they should probably be their own thing.