fix delete_conversations for the audit log

fixes VICE-1277
flag=none

Test Plan:
- Tests pass

Change-Id: If601bf89a9cf3efdcf68972dede4cfe8a3ac98c1
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/261910
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Rob Orton <rob@instructure.com>
QA-Review: Rob Orton <rob@instructure.com>
Product-Review: Rob Orton <rob@instructure.com>

app/graphql/audit_log_field_extension.rb

@@ -136,7 +136,6 @@ class AuditLogFieldExtension < GraphQL::Schema::FieldExtension
       next unless AuditLogFieldExtension.enabled?
 
       mutation = field.mutation
-      next if mutation == Mutations::DeleteConversations
       next if mutation == Mutations::AddConversationMessage
 
       logger = Logger.new(mutation, context, arguments)

app/graphql/mutations/delete_conversations.rb

@@ -28,6 +28,7 @@ class Mutations::DeleteConversations < Mutations::BaseMutation
 
   def resolve(input:)
     errors = {}
+    context[:deleted_models] = {conversations: {}}
     # rubocop:disable Style/BlockDelimiters
     resolved_ids = input[:ids].map { |id|
       conversation = Conversation.find_by(id: id)
@@ -43,6 +44,7 @@ class Mutations::DeleteConversations < Mutations::BaseMutation
       end
 
       participant_record.remove_messages(:all)
+      context[:deleted_models][:conversations][conversation.id] = conversation
       conversation.id
     }.compact
     # rubocop:enable Style/BlockDelimiters
@@ -54,4 +56,8 @@ class Mutations::DeleteConversations < Mutations::BaseMutation
   rescue ActiveRecord::RecordInvalid => e
     errors_for(e.record)
   end
+
+  def self.conversation_ids_log_entry(entry, context)
+    context[:deleted_models][:conversations][entry]
+  end
 end