[8.0] Prevent 6.8 indices upgrade to 8.0 (#82689)#82876

grcevski merged 3 commits intoelastic:8.0elastic/elasticsearch:8.0from

grcevski:backport/8_0_prevent_6.8_indices_upgradegrcevski/elasticsearch:backport/8_0_prevent_6.8_indices_upgradeCopy head branch name to clipboard