Rename config_template.yaml to something else

https://github.com/indeedeng/iwf/blob/15c814463211b3119f56373cfb124b4559ae3c6e/script/start-server.sh#L3

But that will be a minor breaking changes for whoever has used this in production

See history of it: https://github.com/indeedeng/iwf/pull/562#discussion_r2049505811

Start with line 3 of script/start-server.sh and review the discussion linked from pull request 562. Determine the replacement name for config_template.yaml and how the minor production breaking change should be handled. Done means the rename and its impact are addressed consistently.

Written by the indexing model from the issue text.