style(tools/dns): improve code style for readability (#12808)

kong/tools/dns.lua

@@ -1,6 +1,7 @@
-local utils = require "kong.tools.utils"
+local normalize_ip = require("kong.tools.ip").normalize_ip
 local dns_client
 
+
 --- Load and setup the DNS client according to the provided configuration.
 -- @param conf (table) Kong configuration
 -- @return the initialized `resty.dns.client` module, or an error
@@ -15,7 +16,7 @@ local setup_client = function(conf)
   -- servers must be reformatted as name/port sub-arrays
   if conf.dns_resolver then
     for i, server in ipairs(conf.dns_resolver) do
-      local s = utils.normalize_ip(server)
+      local s = normalize_ip(server)
       servers[i] = { s.host, s.port or 53 }   -- inserting port if omitted
     end
   end
@@ -41,4 +42,5 @@ local setup_client = function(conf)
   return dns_client
 end
 
+
 return setup_client