Improve test assertion to be more precise

Co-authored-by: swissspidy <841956+swissspidy@users.noreply.github.com>

Author: Copilot

features/cron-event.feature

@@ -195,9 +195,5 @@ Feature: Manage WP Cron events
       """
     And STDOUT should contain:
       """
-      Success: Executed a total of 2 cron events across
-      """
-    And STDOUT should contain:
-      """
-      sites.
+      Success: Executed a total of 2 cron events across 3 sites.
       """