chore(e2e): Fix sentinel dialog purge (#1546)

Did not remove IDs that were successfully purged

#1547 

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **Bug Fixes**
- Improved the logic for purging dialogs to ensure only failed purges
are retained for further inspection.
- Streamlined logging by removing unnecessary output upon purge failure.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

tests/k6/common/sentinel.js

@@ -27,13 +27,14 @@ export default function () {
 
         if (dialogIdsToPurge.length > 0) {
             console.error("Found " + dialogIdsToPurge.length + " unpurged dialogs, make sure that all tests clean up after themselves. Purging ...");
-            dialogIdsToPurge.forEach((id) => {
+            dialogIdsToPurge = dialogIdsToPurge.filter((id) => {
                 console.warn("Sentinel purging dialog with id: " + id)
                 let r = purgeSO('dialogs/' + id, null, tokenOptions);
                 if (r.status != 204) {
                     console.error("Failed to purge dialog with id: " + id);
-                    console.log(r);
+                    return true; // Keep in the array if purge failed
                 }
+                return false; // Remove from the array if purge succeeded
             });
         }