Change want_spam to list of symbols_enabled (#3304)

* Change want_spam to list of symbols_enabled

want_spam disable all mail processing by RspamD, so DKIM signing is not applied for any mail where rcpt is /postmaster@*/, including external one.

* Update preset_2.yml

Co-authored-by: André Peters <andre.peters@debinux.de>

data/web/inc/presets/rspamd/preset_2.yml

@@ -2,4 +2,9 @@ headline: lang.rsettings_preset_2
 content: |
   priority = 10;
   rcpt = "/postmaster@.*/";
-  want_spam = yes;
+  apply {
+    symbols_enabled = ["DKIM_SIGNED", "HISTORY_SAVE", "MILTER_HEADERS", "ARC_SIGNED"];
+  actions {
+      greylist = null;
+    }
+  }