Remove cacheKeyRenderer from IndicesRequestCache

[tvernum]

IndicesRequestCache has this comment:

    // NORELEASE The cacheKeyRenderer has been added in order to debug
    // https://github.com/elastic/elasticsearch/issues/32827, it should be
    // removed when this issue is solved

Since #32827 is closed, can we drop the cacheKeyRenderer argument (or remove the comment if we've decided to keep it permanently)?

[elasticmachine]

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

[tvernum]

Ping @jimczi since it seems you fixed the issue that this was intending to diagnose.