Return false instead of throwing when event stream does not exist (#20165)

## Summary

- When an event stream expires (TTL), `addQueryToEventStream` and
`removeQueryFromEventStream` now return `false` instead of throwing
`EVENT_STREAM_DOES_NOT_EXIST` as an `InternalServerError`
- Frontend checks the mutation return value and triggers the
destroy/recreate cycle, same recovery behavior without the error path
- Removes `EVENT_STREAM_DOES_NOT_EXIST` from exception code, exception
filter, and frontend graceful error check since it's no longer thrown

## Test plan

- [x] Verify that when an event stream TTL expires, the frontend
silently recreates the stream without error noise in logs/Sentry
- [x] Verify that `NOT_AUTHORIZED` errors still throw correctly on both
mutations
- [ ] Verify that the subscription `onEventSubscription` still works
end-to-end with stream creation, query registration, and heartbeat TTL
refresh

Made with [Cursor](https://cursor.com)

packages/twenty-server/src/engine/subscriptions/event-stream.resolver.ts

@@ -151,11 +151,9 @@ export class EventStreamResolver {
     );
 
     if (!isDefined(streamData)) {
-      throw new EventStreamException(
-        'Event stream does not exist',
-        EventStreamExceptionCode.EVENT_STREAM_DOES_NOT_EXIST,
-      );
+      return false;
     }
+
     const isAuthorized = await this.eventStreamService.isAuthorized({
       streamData,
       authContext: {
@@ -170,6 +168,7 @@ export class EventStreamResolver {
         EventStreamExceptionCode.NOT_AUTHORIZED,
       );
     }
+
     await this.eventStreamService.addQuery({
       workspaceId: workspace.id,
       eventStreamChannelId,
@@ -197,10 +196,7 @@ export class EventStreamResolver {
     );
 
     if (!isDefined(streamData)) {
-      throw new EventStreamException(
-        'Event stream does not exist',
-        EventStreamExceptionCode.EVENT_STREAM_DOES_NOT_EXIST,
-      );
+      return false;
     }
 
     const isAuthorized = await this.eventStreamService.isAuthorized({