Remove support for query_binary and filter_binary

[javanna]

query_binary and filter_binary are unused at this point, as we only parse on the coordinating node and the java api only holds structured java objects for queries and filters, meaning they all implement Writeable and get natively serialized.

Relates to #14308

[dakrone]

LGTM, but should be marked as "breaking" and noted in the migration guide?

[javanna]

should be marked as "breaking" and noted in the migration guide?

not really, we are just removing support for something that is at this time unused and was never documented. Last bit of the actual removal was part of #14384 with the removal of QuerySourceBuilder, which used query_binary internally and required it to be supported in core.

[dakrone]

we are just removing support for something that is at this time unused and was never documented

From the code it looks like someone could send query_binary or queryBinary at the REST layer, is that correct? If so, I definitely think we should mark/document this as breaking, because even though we don't think anyone uses it, someone could be.

[javanna]

Sure the feature is exposed to the outside world, I can mark breaking just to make sure, but it feels very weird to document that we removed it given that we never documented before, and we couldn't even deprecate in 2.x for the very same reason. This feature made sense only internally since the java api allowed to provide queries as binary objects, it should be treated as an internal thing as it was up until now.