Rewrite upper bound of time range of shard request

[dgieselaar]

Currently, Elasticsearch rewrites a range query on @timestamp to a MatchAll query if all the data on a shard falls within the bounds of the range query. This is great for increasing the amount of shard request cache hits.

To increase the cache hit ratio, ES could consider rewriting the upper bound of a query to its max value for @timestamp. In a sliding window scenario, where the consumers of the _search API round down the lower end of a time range, e.g. for a now-7d time range they will round down to the hour, the cache hit ratio on the index at the start of the time range will be increased.

[elasticmachine]

Pinging @elastic/es-search (Team:Search)

[elasticsearchmachine]

Pinging @elastic/es-search-foundations (Team:Search Foundations)