kandra: Ensure that we do not error out creating standby.signal.

Force us to have restored the `/var/lib/postgresql/14/main` directory
before we try to create `standby.signal` in it.

puppet/kandra/manifests/profile/postgresql.pp

@@ -50,6 +50,7 @@ class kandra::profile::postgresql inherits kandra::profile::base {
       require => [File['/usr/local/bin/env-wal-g'], Exec['setup_disks']],
       unless  => "test -d /srv/data/postgresql/${zulip::postgresql_common::version}/main",
       timeout => 0,
+      before  => File["${zulip::postgresql_base::postgresql_datadir}/standby.signal"],
       notify  => Exec[$zulip::postgresql_base::postgresql_restart],
     }
   }

puppet/zulip/manifests/profile/postgresql.pp

@@ -59,6 +59,7 @@ class zulip::profile::postgresql {
     file { "${zulip::postgresql_base::postgresql_datadir}/standby.signal":
       ensure  => file,
       require => Package[$zulip::postgresql_base::postgresql],
+      before  => Exec[$zulip::postgresql_base::postgresql_restart],
       owner   => 'postgres',
       group   => 'postgres',
       mode    => '0644',