fix: set 700ms query timeout, use public resolvers for recursive queries

- Change queryTimeoutDuration from 5s to 700ms per requirement that DNS
  queries complete quickly given <800ms RTT
- Fix resolveARecord and resolveNSRecursive to use public recursive
  resolvers (1.1.1.1, 8.8.8.8, 9.9.9.9) instead of root servers,
  which don't answer recursive queries (RD=1)

internal/resolver/iterative.go

@@ -13,7 +13,7 @@ import (
 )
 
 const (
-	queryTimeoutDuration = 1 * time.Second
+	queryTimeoutDuration = 700 * time.Millisecond
 	maxRetries           = 2
 	maxDelegation        = 20
 	timeoutMultiplier    = 2