As a replacement use ExistsQueryBuilder inside a mustNot() clause.
So instead of using `new ExistsQueryBuilder(name)` now use:
`new BoolQueryBuilder().mustNot(new ExistsQueryBuilder(name))`.
Closes#14112
In the example we show an `exists` query inside a constant score query. While this is possible, it can mislead users to think it is necessary so we should remove it.
This commit makes queries and filters parsed the same way using the
QueryParser abstraction. This allowed to remove duplicate code that we had
for similar queries/filters such as `range`, `prefix` or `term`.
Adrien Grand
Jim Ferenczi
Christoph Büscher
Clinton Gormley