Stop throwing for event stream does not exists (#20008)

Fixes
https://twenty-v7.sentry.io/issues/7351816489/?environment=prod&environment=prod-eu&project=4507072499810304&query=is%3Aunresolved%20%21issue.type%3A%5Bperformance_consecutive_db_queries%2Cperformance_consecutive_http%2Cperformance_file_io_main_thread%2Cperformance_db_main_thread%2Cperformance_n_plus_one_db_queries%2Cperformance_n_plus_one_api_calls%2Cperformance_p95_endpoint_regression%2Cperformance_slow_db_query%2Cperformance_render_blocking_asset_span%2Cperformance_uncompressed_assets%2Cperformance_http_overhead%2Cperformance_large_http_payload%5D%20timesSeen%3A%3E10&referrer=issue-stream&sort=date

- When an SSE event stream already exists in Redis during a
reconnection, the server now checks if the caller is the rightful owner
(via isAuthorized) and destroys the stale stream before creating a fresh
one, instead of throwing an EVENT_STREAM_ALREADY_EXISTS error
- Unauthorized callers still receive the error, preserving the security
guard against hijacking

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

@@ -64,16 +64,31 @@ export class EventStreamResolver {
   ) {
     const eventStreamChannelId = eventStreamIdToChannelId(eventStreamId);
 
-    const streamData = await this.eventStreamService.getStreamData(
+    const existingStreamData = await this.eventStreamService.getStreamData(
       workspace.id,
       eventStreamChannelId,
     );
 
-    if (isDefined(streamData)) {
-      throw new EventStreamException(
-        'Event stream already exists',
-        EventStreamExceptionCode.EVENT_STREAM_ALREADY_EXISTS,
-      );
+    if (isDefined(existingStreamData)) {
+      const isAuthorized = await this.eventStreamService.isAuthorized({
+        streamData: existingStreamData,
+        authContext: {
+          userWorkspaceId,
+          apiKeyId: apiKey?.id,
+        },
+      });
+
+      if (!isAuthorized) {
+        throw new EventStreamException(
+          'Event stream already exists',
+          EventStreamExceptionCode.EVENT_STREAM_ALREADY_EXISTS,
+        );
+      }
+
+      await this.eventStreamService.destroyEventStream({
+        workspaceId: workspace.id,
+        eventStreamChannelId,
+      });
     }
 
     await this.eventStreamService.createEventStream({