puppet: Raise net.core.somaxconn on redis.

puppet/zulip_ops/manifests/profile/redis.pp

@@ -2,6 +2,11 @@ class zulip_ops::profile::redis inherits zulip_ops::profile::base {
   include zulip::profile::redis
   include zulip_ops::prometheus::redis
 
+  zulip::sysctl { 'redis-somaxconn':
+    key   => 'net.core.somaxconn',
+    value => '65535',
+  }
+
   # Need redis_password in its own file for Nagios
   file { '/var/lib/nagios/redis_password':
     ensure  => file,