fix(monitoring): widen OpenBaoUnavailable for: 1m -> 5m (REN-131)

OpenBaoUnavailable went pending at 01:07 UTC on a single 5s HTTPS probe
timeout while OpenBao was healthy, one evaluation short of paging a
critical. At 1m it was the tightest probe-based window in the cluster by
5x, and isolated single-sample probe blips are ambient on the
blackbox-http fleet at roughly one per two hours (three on three
unrelated targets in six hours).

5m matches WoodpeckerDown in the same group. Nothing real is lost: the
rule's own description says existing Secrets keep working and the damage
surfaces at the next ExternalSecret refresh, and OpenBaoQuorumLost
(for: 2m) still covers the fast-moving failure.

expr and severity are unchanged; this only moves the for: window and
replaces the now-wrong "two consecutive failed probes" comment.

Co-Authored-By: Paperclip <noreply@paperclip.ing>
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

kubernetes/apps/monitoring-rules/prometheusrule-ci-openbao.yaml

@@ -34,9 +34,20 @@ spec:
           # query parameter, and an exact match would break silently if the
           # instance label ever encodes it differently.
           expr: probe_success{job="blackbox-http", instance=~"https://openbao\\.renner\\.uno/v1/sys/health.*"} == 0
-          # Two consecutive failed probes: enough to skip a single lost probe
-          # through Traefik, not enough to sit on a sealed store.
-          for: 1m
+          # Five minutes of continuously failing probes — about ten consecutive
+          # samples, since the probe and the rule evaluation both run at 30s
+          # (probes-blackbox.yaml, helmrelease-prometheus.yaml). Matches
+          # WoodpeckerDown above.
+          #
+          # This was 1m, the tightest probe window in the cluster by 5x, and it
+          # went pending on a single 5s HTTPS timeout with OpenBao healthy
+          # (REN-131). Isolated blips are ambient on this probe fleet at roughly
+          # one per two hours, so a window that clears on three samples pages on
+          # jitter. The widening costs nothing real: per the description below
+          # nothing breaks the moment OpenBao goes away, and OpenBaoQuorumLost
+          # (prometheusrule-openbao.yaml, for: 2m) still covers the fast
+          # failure, which is quorum loss rather than a lost probe.
+          for: 5m
           labels:
             severity: critical
           annotations: