fix(severity.yaml): change nosqlbench severity
fix(severity.yaml): change nosqlbench severity

NoSQLBenchStressLogEvents.ProgressIndicatorRunningEvent
added on PR #4015 used severity DEBUG, but it is meant for
some specific use, hence moving it to be normal events instead.

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