ADD BROKER LIST FILE TO REPLACE HARDCODE BASH LIST

[howard-tran]

Description

What behavior does this PR change, and why?

I add a broker list file to replace these hardcode syntax

users=(kafka1 kafka2)

if [[ "$i" == "mds" ]]; then
  DNS_ALT_NAMES=$(printf '%s\n' "$DNS_ALT_NAMES" "DNS.3 = kafka1" "DNS.4 = kafka2")
fi

Author Validation

Describe the validation already done, or needs to be done, by the PR submitter.

I run the setup on google cloud shell, here is the proof

Reviewer Tasks

Describe the tasks/validation that the PR submitter is requesting to be done by the reviewer.