fix: Locale not correct in root url when accessing help center with custom domain (#9110)

- Ensuring that SwitchLocale concern handles the case of custom domain for portals and set locale according to that

Co-authored-by: Sojan Jose <sojan@pepalo.com>

app/controllers/concerns/domain_helper.rb

@@ -0,0 +1,5 @@
+module DomainHelper
+  def self.chatwoot_domain?(domain = request.host)
+    [URI.parse(ENV.fetch('FRONTEND_URL', '')).host, URI.parse(ENV.fetch('HELPCENTER_URL', '')).host].include?(domain)
+  end
+end