Allow LDAP `sync_ssh_keys` setting to be set to `true`

In that case `sync_ssh_keys` will default to the `sshPublicKey` value.

CHANGELOG-EE

@@ -8,6 +8,7 @@ v 8.11.0 (unreleased)
   - Optimize commit and diff changes access check to reduce git operations
   - Allow syncing a group against all providers at once
   - Change LdapGroupSyncWorker to use new LDAP group sync classes
+  - Allow LDAP `sync_ssh_keys` setting to be set to `true`
   - Removed unused GitLab GEO database index
   - Enable monitoring for ES classes
   - [Elastic] Improve code search

config/initializers/1_settings.rb

@@ -166,6 +166,7 @@ if Settings.ldap['enabled'] || Rails.env.test?
     server['provider_name'] ||= "ldap#{key}".downcase
     server['provider_class'] = OmniAuth::Utils.camelize(server['provider_name'])
     server['external_groups'] = [] if server['external_groups'].nil?
+    server['sync_ssh_keys'] = 'sshPublicKey' if server['sync_ssh_keys'].to_s == 'true'
     Settings.ldap['servers'][key] = server
   end
 end