Backend scripts don't support running on multiple nodes

Many start scripts don't support running on multiple nodes, even if the --nodelist argument is passed.

For example, for the command

"${KAFKA_BIN_PATH}/kafka-broker-api-versions.sh" \
  --bootstrap-server "${KAFKA_SLURM_NODELIST}:${KAFKA_BROKER_PORT}"

for now, the KAFKA_SLURM_NODELIST comes from SLURM and is in a format like:

c[1262,1266]

which is not valid for most of the Kafka's --bootstrap-server parameter, so Kafka sees this literal string:

c[1262,1266]:9092

Kafka will fail to resolve this as a valid hostname. We need to convert KAFKA_SLURM_NODELIST into a comma-separated list of actual hostnames, like:

c1262:9092,c1266:9092

A possible fix to this can be

  NODES=$(scontrol show hostname "$KAFKA_SLURM_NODELIST")
  # Append port and join into comma-separated list
  BROKER_LIST=$(printf "%s:${KAFKA_BROKER_PORT}," $NODES | sed 's/,$//')

...

"\"${KAFKA_BIN_PATH}/kafka-broker-api-versions.sh\" --bootstrap-server "$BROKER_LIST" >/dev/null 2>&1"