Synapse: Allow unencrypted private rooms
Private rooms are already end-to-end-encrypted (E2EE) by default (at least if created via Element - didn't test other clients). However the synapse setting encryption_enabled_by_default_for_room_type: invite led Element to disallow creating private rooms without E2EE (i.e. the encryption setting was force-enabled). With the default setting in Synapse (off) Element will still enable encryption by default, but it can be disabled at room creation time.