Kibana version:

main (8.5.0)

Original install method (e.g. download page, yum, from source, etc.):

from source

Describe the bug:

The options on alerts include "Adding to existing case" even when there are no existing cases.

Steps to reproduce:

1. Go to Observability
2. Create a rule that would trigger alerts
3. Make sure there is no existing case
4. Go to the alerts page and click on an 3dots menu on one of the alerts

Expected behavior:

Only relevant options are shown in the menu, i.e. options that can be done.