CI Failure (key symptom) in `FlexibleCompatTest.test_api_versions_flexible`

https://buildkite.com/redpanda/vtools/builds/15889

Module: rptest.tests.flexible_compat_test
Class: FlexibleCompatTest
Method: test_api_versions_flexible

test_id:    FlexibleCompatTest.test_api_versions_flexible
status:     FAIL
run time:   8.093 seconds

SSHException('Error reading SSH protocol banner')
Traceback (most recent call last):
  File "/opt/.ducktape-venv/lib/python3.10/site-packages/paramiko/transport.py", line 2327, in _check_banner
    buf = self.packetizer.readline(timeout)
  File "/opt/.ducktape-venv/lib/python3.10/site-packages/paramiko/packet.py", line 381, in readline
    buf += self._read_timeout(timeout)
  File "/opt/.ducktape-venv/lib/python3.10/site-packages/paramiko/packet.py", line 618, in _read_timeout
    raise EOFError()
EOFError

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/opt/.ducktape-venv/lib/python3.10/site-packages/ducktape/tests/runner_client.py", line 182, in _do_run
    self.setup_test()
  File "/opt/.ducktape-venv/lib/python3.10/site-packages/ducktape/tests/runner_client.py", line 267, in setup_test
    self.test.setup()
  File "/opt/.ducktape-venv/lib/python3.10/site-packages/ducktape/tests/test.py", line 91, in setup
    self.setUp()
  File "/home/ubuntu/redpanda/tests/rptest/tests/redpanda_test.py", line 39, in setUp
    self.__redpanda.start()
  File "/home/ubuntu/redpanda/tests/rptest/services/redpanda.py", line 2696, in start
    self.for_nodes(self.nodes, clean_one)
  File "/home/ubuntu/redpanda/tests/rptest/services/redpanda.py", line 1489, in for_nodes
    return list(executor.map(cb, nodes))
  File "/usr/lib/python3.10/concurrent/futures/_base.py", line 621, in result_iterator
    yield _result_or_cancel(fs.pop())
  File "/usr/lib/python3.10/concurrent/futures/_base.py", line 319, in _result_or_cancel
    return fut.result(timeout)
  File "/usr/lib/python3.10/concurrent/futures/_base.py", line 451, in result
    return self.__get_result()
  File "/usr/lib/python3.10/concurrent/futures/_base.py", line 403, in __get_result
    raise self._exception
  File "/usr/lib/python3.10/concurrent/futures/thread.py", line 58, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/home/ubuntu/redpanda/tests/rptest/services/redpanda.py", line 2683, in clean_one
    self.clean_node(node, preserve_current_install=True)
  File "/home/ubuntu/redpanda/tests/rptest/services/redpanda.py", line 3803, in clean_node
    node.account.kill_process("redpanda",
  File "/opt/.ducktape-venv/lib/python3.10/site-packages/ducktape/cluster/remoteaccount.py", line 422, in kill_process
    pids = [pid for pid in self.ssh_capture(cmd, allow_fail=True)]
  File "/opt/.ducktape-venv/lib/python3.10/site-packages/ducktape/cluster/remoteaccount.py", line 41, in wrapper
    return method(self, *args, **kwargs)
  File "/opt/.ducktape-venv/lib/python3.10/site-packages/ducktape/cluster/remoteaccount.py", line 331, in ssh_capture
    client = self.ssh_client
paramiko.ssh_exception.SSHException: Error reading SSH protocol banner

JIRA Link: CORE-5755

redpanda-data / redpanda

CI Failure (key symptom) in `FlexibleCompatTest.test_api_versions_flexible` #21592