MINOR: Need to split the controller bootstrap servers on ',' in list …

…comprehenson (#17183)

Kafka Streams system tests were failing with this error:

Failed to parse host name from entry 3001@d for the configuration controller.quorum.voters.  Each entry should be in the form `{id}@{host}:{port}`.

The cause is that in kafka.py line 876, we create a delimited string from a list comprehension, but the input is a string itself, so each character gets appended vs. the bootstrap server string of host:port. To fix this, this PR adds split(',') to controller_quorum_bootstrap_servers. Note that this only applies when dynamicRaftQuorum=False

Reviewers: Alyssa Huang <[email protected]>, Chia-Ping Tsai <[email protected]>

tests/kafkatest/services/kafka/kafka.py

@@ -875,7 +875,7 @@ def start_node(self, node, timeout_sec=60, **kwargs):
             else:
                 self.controller_quorum_voters = ','.join(["%s@%s" % (self.controller_quorum.idx(node) + first_node_id - 1,
                                                                      bootstrap_server)
-                                                          for bootstrap_server in controller_quorum_bootstrap_servers])
+                                                          for bootstrap_server in controller_quorum_bootstrap_servers.split(',')])
             # define controller.listener.names
             self.controller_listener_names = ','.join(self.controller_listener_name_list(node))
             # define sasl.mechanism.controller.protocol to match the isolated quorum if one exists