There is little evidence of this endpoint being used
and there is quite a lot of code complexity associated
with the various formats that can be used to upload
data and the different errors that can occur when direct
data upload is open to end users.
In a future release we can make this endpoint internal
so that only datafeeds can use it, and remove all the
options and formats that are not used by datafeeds.
End users will have to store their input data for
anomaly detection in Elasticsearch indices (which we
believe all do today) and use a datafeed to feed it
to anomaly detection jobs.
Backport of #66347
