RelatednessAgg ignores cacheDf, consults filterCache for every bucket/term

The relatedness aggregation function in JSON facet API ignores cacheDf setting and consults the filterCache for every bucket. This is ok e.g. for "Query" facet type, where buckets are explicitly enumerated (and thus probably relatively low cardinality). But for "Terms" facet type, where bucket count is determined by the corpus, this can be a problem. When used over even modestly high-cardinality fields, this is very likely to blow out the filterCache.

See also issue with similar consequences: SOLR-9350