Remove unspecced GET endpoints for e2e keys
Remove unspecced GET endpoints for e2e keys

GET /keys/claim is a terrible idea, since it isn't idempotent; also it throws
500 errors if you call it without all the right params.

GET /keys/query is arguable, but it's unspecced, so let's get rid of it too to
stop people relying on unspecced APIs.

matrix-org/synapse,matrix-org/synapse,matrix-org/synapse,TribeMedia/synapse,matrix-org/synapse,matrix-org/synapse,TribeMedia/synapse,TribeMedia/synapse,TribeMedia/synapse,TribeMedia/synapse,matrix-org/synapse