Cleanup RFS source and target versions, add support for RFS 5.x, 7.x target with same-version migrations#1373

AndreKurait merged 6 commits intoopensearch-project:mainopensearch-project/opensearch-migrations:mainfrom

AndreKurait:AddES5and7TargetExpirimentalRFSOnlySupportAndreKurait/opensearch-migrations:AddES5and7TargetExpirimentalRFSOnlySupportCopy head branch name to clipboard