LTR Queries don't use queryResultCache

Before queries are placed in the query result cache, they get rewritten. Sometimes this rewriting happens in-place. The key used for the query result cache, has as one element, the query.

For LTRQuery -> LTRScoringQuery, rewriting will change the cache key's original query. Thus when we insert using this key, it's not the same as subsequent queries that perform a lookup. So LTRQueries never benefit from the cache.

A similar issue was resolved with general reranking queries by jbernste 

SOLR-7689 - https://issues.apache.org/jira/browse/SOLR-7689