[Minor] Improve logic to select a random monitored mode for RBLs

src/plugins/lua/rbl.lua

@@ -47,21 +47,26 @@ local known_selectors = {} -- map from selector string to selector id
 local url_flag_bits = rspamd_url.flags
 
 local function get_monitored(rbl)
+  local function is_random_monitored()
+    return (rbl.dkim
+        or rbl.urls
+        or rbl.emails
+        or rbl.no_ip
+        or rbl.rdns
+        or rbl.helo)
+  end
+
   local default_monitored = '1.0.0.127'
   local ret = {
     rcode = 'nxdomain',
     prefix = default_monitored,
-    random = false,
+    random = is_random_monitored(),
   }
 
   if rbl.monitored_address then
     ret.prefix = rbl.monitored_address
   end
 
-  if rbl.dkim or rbl.urls or rbl.emails then
-    ret.random = true
-  end
-
   lua_util.debugm(N, rspamd_config,
       'added monitored address: %s (%s random)',
       ret.prefix, ret.random)