Revert changes to conversation_attribute_updated_by_workflow schema

Remove the incorrectly added previous field from conversation_attribute_updated_by_workflow -
this feature was never implemented (PRs #432721 and #433432 were closed without merging).

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: VedranZoricic

descriptions/0/api.intercom.io.yaml

@@ -19806,13 +19806,8 @@ components:
           properties:
             name:
               type: string
-              description: Current value of the CDA updated
+              description: Value of the CDA updated
               example: vip_status
-            previous:
-              type: string
-              nullable: true
-              description: Previous value of the CDA (null for older events)
-              example: regular_status
     conversation_attribute_updated_by_admin:
       title: Part type - conversation_attribute_updated_by_admin
       type: object