Intermediary queries in sequences and samples should not ask for all fields to be returned

[astefan]

Description

QueryFolder shouldn’t use the default EsQueryExec output() method, but SampleExec and SequenceExec’s output() method instead. As is, the intermediary queries use fields API referencing all fields from the index, whereas it should only use those fields specific to a sequence or sample.

[elasticmachine]

Pinging @elastic/es-ql (Team:QL)

[luigidellaquila]

This problem was fixed in samples with #88833, now only join keys are returned by intermediary queries.

For sequences, the implementation was already in place: intermediary queries only return the needed fields