In the upcoming Lucene 9 release, `indices.query.bool.max_clause_count` is
going to apply to the entire query tree rather than per `bool` query. In order
to avoid breaks, the limit has been bumped from 1024 to 4096.
The semantics will effectively change when we upgrade to Lucene 9, this PR
is only about agreeing on a migration strategy and documenting this change.
To avoid further breaks, I am leaning towards keeping the current setting name
even though it contains `bool`. I believe that it still makes sense given that
`bool` queries are typically the main contributors to high numbers of clauses.
Co-authored-by: James Rodewig <40268737+jrodewig@users.noreply.github.com>
feb6620d14