correct the node that nodetool executes on
correct the node that nodetool executes on

The node that nodetool executes on is configurable, not always be the target
node. In one terminate_and_replace_node nemesis, the target node has been terminated,
it caused _run_nodetool() failed.

Traceback (most recent call last):
  File "/sct/sdcm/nemesis.py", line 753, in wrapper
    result = method(*args, **kwargs)
  File "/sct/sdcm/nemesis.py", line 906, in disrupt
    self.call_random_disrupt_method()
  File "/sct/sdcm/nemesis.py", line 444, in call_random_disrupt_method
    disrupt_method()
  File "/sct/sdcm/nemesis.py", line 304, in disrupt_terminate_and_replace_node
    self.repair_nodetool_repair(new_node)
  File "/sct/sdcm/nemesis.py", line 458, in repair_nodetool_repair
    self._run_nodetool(repair_cmd, node)
  File "/sct/sdcm/nemesis.py", line 132, in _run_nodetool
    (cmd, self.target_node, details.result))
  File "/sct/sdcm/cluster.py", line 670, in __str__
    self.public_ip_address,
  File "/sct/sdcm/cluster_aws.py", line 288, in public_ip_address
    return self._instance.public_ip_address
  File "/usr/lib/python2.7/site-packages/boto3/resources/factory.py", line 345, in property_loader
    return self.meta.data.get(name)
AttributeError: 'NoneType' object has no attribute 'get'

Signed-off-by: Amos Kong <eb01d8f828a6c9a20be4534e72e049aaf41503df@scylladb.com>

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