chore: Apply fixes for items in rubocop_todo [CW-1806] (#8864)

This PR addresses several items listed in our rubocop_todo by implementing the necessary corrections and enhancements. As a result, we are now able to remove the rubocop_todo file entirely, streamlining our codebase and ensuring adherence to our coding standards.

fixes: https://linear.app/chatwoot/issue/CW-1806/chore-rubocop-audit

app/models/attachment.rb

@@ -38,7 +38,8 @@ class Attachment < ApplicationRecord
   has_one_attached :file
   validate :acceptable_file
   validates :external_url, length: { maximum: Limits::URL_LENGTH_LIMIT }
-  enum file_type: [:image, :audio, :video, :file, :location, :fallback, :share, :story_mention, :contact]
+  enum file_type: { :image => 0, :audio => 1, :video => 2, :file => 3, :location => 4, :fallback => 5, :share => 6, :story_mention => 7,
+                    :contact => 8 }
 
   def push_event_data
     return unless file_type