Remove research outputs when types have changed to be unsupported.

[nihiliad]

Research output with uuid c8457687-c06b-4289-8e5f-9b21aae34d84 seems to be giving us problems because its type has changed. Right now we support only "contribution to journal" types, so its type must have been one of those when we first downloaded it. But now its type uri is /dk/atira/pure/researchoutput/researchoutputtypes/contributiontoconference/paper, so a "contribution to conference" type, which we don't support. This is likely why transformer_loaders/pure_api_pub is having trouble transforming it.

The reverse has also happened, in which a research output is changed from an unsupported type to a supported type.