[0.17.0] Speed up String first/last aggregators when folding isn't needed. (#9181)#9215

clintropolis merged 3 commits intoapache:0.17.0apache/druid:0.17.0from

suneet-s:backport/0.17.0/pr-9181suneet-s/druid:backport/0.17.0/pr-9181Copy head branch name to clipboard