fix: sanitize integer fields to prevent Elasticsearch mapping errors (#13276)

## Linear task:

https://linear.app/chatwoot/issue/CW-6318/searchkickimporterror-type-=-mapper-parsing-exception-reason-=-failed

## Description

Fixes Elasticsearch `mapper_parsing_exception` errors that occur when
`campaign_id` contain non-numeric string values

## Type of change

- [x] Bug fix (non-breaking change which fixes an issue)

## How Has This Been Tested?

- Unit tests
- use a local OpenSearch 3.4.0 cluster to verify actual indexing
behavior.


## Checklist:

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules


<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Removes `campaign_id` from the message search index payload to
simplify `additional_attributes`, keeping only `automation_rule_id`.
> 
> - `Messages::SearchDataPresenter#additional_attributes_data` now
returns only `automation_rule_id`
> - Specs updated to stop asserting `campaign_id` and continue
validating `automation_rule_id` and email subject handling
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
5a9c8eb794a044e3f258b644f67a6731de9e904c. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

app/presenters/messages/search_data_presenter.rb

@@ -51,7 +51,6 @@ class Messages::SearchDataPresenter < SimpleDelegator
 
   def additional_attributes_data
     {
-      campaign_id: additional_attributes&.dig('campaign_id'),
       automation_rule_id: content_attributes&.dig('automation_rule_id')
     }
   end

spec/presenters/messages/search_data_presenter_spec.rb

@@ -61,15 +61,10 @@ RSpec.describe Messages::SearchDataPresenter do
     context 'with campaign and automation data' do
       before do
         message.update(
-          additional_attributes: { 'campaign_id' => '123' },
           content_attributes: { 'automation_rule_id' => '456' }
         )
       end
 
-      it 'includes campaign_id' do
-        expect(presenter.search_data[:additional_attributes][:campaign_id]).to eq('123')
-      end
-
       it 'includes automation_rule_id' do
         expect(presenter.search_data[:additional_attributes][:automation_rule_id]).to eq('456')
       end