puppet: Make zulipconf() understand coercion to bool.

If the default is a bool, coerce the value into a bool as well.  For
backwards compatibility, this does not adjust any existing callsites.

`queue_workers_multiprocess` is the only setting which is passed a
bool default, but it was already documented to take `true` or `false`;
simplify it to no longer add the now-unnecessary Boolean conversion.

(cherry picked from part of commit 2c5fc1827c)

puppet/zulip/lib/puppet/parser/functions/zulipconf.rb

@@ -5,7 +5,12 @@ module Puppet::Parser::Functions
     zulip_conf_path = lookupvar("zulip_conf_path")
     output = `/usr/bin/crudini --get #{zulip_conf_path} #{joined} 2>&1`; result = $?.success?
     if result
-      output.strip()
+      if [true, false].include? default
+        # If the default is a bool, coerce into a bool
+        ['1','y','t','true','yes','enable','enabled'].include? output.strip.downcase
+      else
+        output.strip
+      end
     else
       default
     end

puppet/zulip/manifests/app_frontend_base.pp

@@ -73,7 +73,7 @@ class zulip::app_frontend_base {
   # multiprocess.  Multiprocess scales much better, but requires more
   # RAM; we just auto-detect based on available system RAM.
   $queues_multiprocess_default = $zulip::common::total_memory_mb > 3500
-  $queues_multiprocess = Boolean(zulipconf('application_server', 'queue_workers_multiprocess', $queues_multiprocess_default))
+  $queues_multiprocess = zulipconf('application_server', 'queue_workers_multiprocess', $queues_multiprocess_default)
   $queues = [
     'deferred_work',
     'digest_emails',