fix flaky streams/streams_broker_bounce_test.py

Module: kafkatest.tests.streams.streams_broker_bounce_test
Class: StreamsBrokerBounceTest
Method: test_broker_type_bounce
Arguments:
{
"broker_type": "leader",
"failure_mode": "clean_bounce",
"num_threads": 1,
"sleep_time_secs": 120
}

Module: kafkatest.tests.streams.streams_broker_bounce_test
Class: StreamsBrokerBounceTest
Method: test_broker_type_bounce
Arguments:
{
"broker_type": "controller",
"failure_mode": "hard_shutdown",
"num_threads": 3,
"sleep_time_secs": 120
}