fix(batched_tests): convert node list into comma seperated list
fix(batched_tests): convert node list into comma seperated list

Both #5061, #4684, tried to add the list of nodes to the stress
commmand, but both wasn't tested with the actuall test case

so we ened up with python list, and not comma seperated list
that is expected:
```
cassandra-stress user profile=/tmp/templated_tables_mvz4no57b5.yaml
cl=QUORUM 'ops(insert=1, read1=5)' duration=55m -rate threads=2 -errors
skip-unsupported-columns ignore -node ['10.4.3.37', '10.4.0.123',
'10.4.2.11', '10.4.0.153', '10.4.2.45', '10.4.0.188']
```

Ref: #5061, #4684

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