fix(perf-pipeline): do not export variable with 'null' value
fix(perf-pipeline): do not export variable with 'null' value

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