fix(common:get_branched_ami): filter out debug-* AMIs
fix(common:get_branched_ami): filter out debug-* AMIs

Following the changes in
https://github.com/scylladb/scylla-machine-image/pull/383 , need to
update the filter with new prefix

to merge only after https://github.com/scylladb/scylla-machine-image/pull/383

scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests