When openning a backport PR, adding a reference to the original PR. This will be used later for updating the original PR/issue once the backport is done (with different label) Closes scylladb/scylladb#17973
When openning a backport PR, adding a reference to the original PR. This will be used later for updating the original PR/issue once the backport is done (with different label) Closes scylladb/scylladb#17973