Fix missing setting LDAP servers

If LDAP is disabled in Omnibus, the LDAP `servers` configuration
hash is not present. GitLab relies on this hash being present
even when LDAP is disabled. Now we initialize the hash on
startup.

changelogs/unreleased/dblessing_fix_ldap_server_config.yml

+---
+title: Fix missing setting LDAP servers
+merge_request: 52512
+author:
+type: fixed

config/initializers/1_settings.rb

@@ -12,6 +12,7 @@ Settings.encrypted_settings['path'] = Settings.absolute(Settings.encrypted_setti
 
 Settings['ldap'] ||= Settingslogic.new({})
 Settings.ldap['enabled'] = false if Settings.ldap['enabled'].nil?
+Settings.ldap['servers'] ||= Settingslogic.new({})
 Settings.ldap['prevent_ldap_sign_in'] = false if Settings.ldap['prevent_ldap_sign_in'].blank?
 Settings.ldap['secret_file'] = Settings.absolute(Settings.ldap['secret_file'] || File.join(Settings.encrypted_settings['path'], "ldap.yaml.enc"))