Description of problem:
There does not appear to be way to clean dnf transaction history
Version-Release number of selected component (if applicable):
"dnf history new" to be implemented
"yum history new" clears transaction history for RHEL 7 and before.
PR to add `history new` command: https://github.com/rpm-software-management/dnf/pull/1541, https://github.com/rpm-software-management/libdnf/pull/854
Restoring previous qa_ack+ as agreed earlier.