fix(mgmt/operator.py): wait till task is created on mgmt
fix(mgmt/operator.py): wait till task is created on mgmt

Since recently s-o create temporarily task_id and when pass it down
 to mgmt changing it to task it that mgmt got it assigned.
This fix will make sct wait ti concreate task is created on mgmt side
 to make sure that task_id is not temporary one.

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