[9.3] ESQL: Fix incorrectly optimized fork with nullify unmapped_fields (#143030)#144205

kanoshiou wants to merge 1 commit intoelastic:9.3elastic/elasticsearch:9.3from

kanoshiou:backport/9.3/pr-143030kanoshiou/elasticsearch:backport/9.3/pr-143030Copy head branch name to clipboard