fix: Identifier not persisted on customer created via Inbox API Channel (#5804)

- Fixes the identifier not being used to identify the contact, this results in having a new contact created every time the email or phone is not supplied.

Fixes: #5704

app/controllers/public/api/v1/inboxes/contacts_controller.rb

@@ -7,7 +7,7 @@ class Public::Api::V1::Inboxes::ContactsController < Public::Api::V1::InboxesCon
     @contact_inbox = ::ContactInboxWithContactBuilder.new(
       source_id: source_id,
       inbox: @inbox_channel.inbox,
-      contact_attributes: permitted_params.except(:identifier, :identifier_hash)
+      contact_attributes: permitted_params.except(:identifier_hash)
     ).perform
   end