Add security_detection_engine into exclude list for observability projects (#184022)

## Summary

Include [`security_detection_engine`
package](d2a74171c8/packages/security_detection_engine)
into the list of excluded packages for Observability projects in Elastic
Serverless.

Relates https://github.com/elastic/integrations/pull/9849
Relates https://github.com/elastic/integrations/pull/9938


### For maintainers

- [x] This was checked for breaking API changes and was [labeled
appropriately](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)

Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>

config/serverless.oblt.yml

@@ -53,6 +53,7 @@ xpack.fleet.internal.registry.excludePackages: [
     # Security integrations
     'endpoint',
     'beaconing',
+    'security_detection_engine',
 
     # Removed in 8.11 integrations
     'cisco',