Insert hints as non-auth into cache, so info received from the net is

recorded in the cache.

Also make sure the root NS refresh happens more often if max-cache-ttl is low.
This is needed as the records no longer maintain the 1000 hours TTL.
In the existing setup, a reprime (with potential outdated info) was done at that
point in time since all root-server address records would expire at the same
time.

Lastly, fix a infinite (caught by depth check) recursion in getBestNSFromCache().

Fixes PowerDNS#10177.

pdns/pdns_recursor.cc

@@ -3514,8 +3514,8 @@ static void houseKeeping(void *)
         }
         last_RC_prune = now.tv_sec;
       }
-      // XXX !!! global
-      if (now.tv_sec - last_rootupdate > 7200) {
+      // Divide by 12 to get the original 2 hour cycle if s_maxcachettl is default (1 day)
+      if (now.tv_sec - last_rootupdate > max(SyncRes::s_maxcachettl / 12, 10U)) {
         int res = SyncRes::getRootNS(g_now, nullptr, 0);
         if (!res) {
           last_rootupdate=now.tv_sec;