refactor: remove triggered_by field from webhook triggers and use automatic sync

- Remove triggered_by field from WorkflowWebhookTrigger model
- Replace manual webhook creation/deletion APIs with automatic sync via WebhookService
- Keep only GET API for retrieving webhook information
- Use same webhook ID for both debug and production environments (differentiated by endpoint)
- Add sync_webhook_relationships to automatically manage webhook lifecycle
- Update tests to remove triggered_by references
- Clean up unused imports and fix type checking issues

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

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

api/core/plugin/entities/request.py

@@ -240,9 +240,11 @@ class RequestFetchAppInfo(BaseModel):
 
     app_id: str
 
+
 class Event(BaseModel):
     variables: Mapping[str, Any]
 
+
 class TriggerInvokeResponse(BaseModel):
     event: Event