fix(full scan): set warning event if full scan failed with timeout
fix(full scan): set warning event if full scan failed with timeout

If Full Scan because of 'Client request timeout.', set WARNING event
instead of ERROR

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