[Backport 2.x] Fix delete index template failed when the index template matches a data stream but is unused#15098

reta merged 2 commits into2.xopensearch-project/OpenSearch:2.xfrom

backport/backport-15080-to-2.xopensearch-project/OpenSearch:backport/backport-15080-to-2.xCopy head branch name to clipboard