fix: Instagram outgoing attachments (#9863)

Fixes
https://linear.app/chatwoot/issue/CW-3497/instagram-outgoing-attachments-are-not-rendering

It seems like Instagram outgoing attachment rendering has been broken
for a long time. We couldn't identify the issue because the check below
only inspects Instagram mentions.
```
metadata[:data_url] = metadata[:thumb_url] = external_url if message.instagram_story_mention?
```
We recently worked on adding the [Instagram CDN URL for
attachments.](https://github.com/chatwoot/chatwoot/pull/9287)

After that, it started using external URLs as attachment data URLs for
both outgoing and incoming attachments. The rendering broken for all the
outgoing attachments since there were no external URLs, making the data
URL empty. Adding an incoming message check will solve the issue.

---------

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

app/models/attachment.rb

@@ -81,7 +81,7 @@ class Attachment < ApplicationRecord
       height: file.metadata[:height]
     }
 
-    metadata[:data_url] = metadata[:thumb_url] = external_url if message.inbox.instagram?
+    metadata[:data_url] = metadata[:thumb_url] = external_url if message.inbox.instagram? && message.incoming?
     metadata
   end
 

spec/models/attachment_spec.rb

@@ -44,9 +44,14 @@ RSpec.describe Attachment do
       }.to_json, headers: {})
     end
 
-    it 'returns external url as data and thumb urls' do
+    it 'returns external url as data and thumb urls when message is incoming' do
       external_url = instagram_message.attachments.first.external_url
       expect(instagram_message.attachments.first.push_event_data[:data_url]).to eq external_url
     end
+
+    it 'returns original attachment url as data url if the message is outgoing' do
+      message = create(:message, :instagram_story_mention, message_type: :outgoing)
+      expect(message.attachments.first.push_event_data[:data_url]).not_to eq message.attachments.first.external_url
+    end
   end
 end