chore(ci): run K8s E2E suite on a weekly schedule (#25119)

chore(ci): run K8s E2E suite weekly instead of nightly

Reduce the schedule from Tue-Sat to once a week (Monday 01:00 UTC).
The suite also runs on PRs that touch K8s-related files and in the
merge queue, so weekly is sufficient for catching regressions.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: pront

.github/workflows/k8s_e2e.yml

@@ -4,7 +4,7 @@
 #    - manual dispatch in GH UI
 #    - on a PR commit if the kubernetes_logs source was changed
 #    - in the merge queue
-#    - on a schedule at midnight UTC Tue-Sat
+#    - on a weekly schedule (Monday 01:00 UTC)
 #    - on demand by either of the following comments in a PR:
 #        - '/ci-run-k8s'
 #        - '/ci-run-all'
@@ -34,7 +34,7 @@ on:
   merge_group:
     types: [checks_requested]
   schedule:
-    - cron: "0 1 * * 2-6" # 01:00 UTC Tue-Sat
+    - cron: "0 1 * * 1" # 01:00 UTC every Monday
 
 concurrency:
   # In flight runs will be canceled through re-trigger in the merge queue, scheduled run, or if