cert-manager: step 5 of 7 — v1.18.6 to v1.19.6 (#0051)

This is the step with the ACME metric label change: the high-cardinality path
label on certmanager_acme_client_request_count and _duration_seconds is replaced
by a bounded action label. Nothing here uses those metrics — neither the
operating stack's rules nor any dashboard references them — so no dashboard or
alert has to follow.

Previous step verified: three deployments on v1.18.6, fifteen certificates
Ready.

apps/base/infra/cert-manager.yaml

@@ -15,7 +15,7 @@ spec:
       # Weg: 1.15.5 -> 1.16.5 -> 1.17.4 -> 1.18.6 -> 1.19.6 -> 1.20.3 -> 1.21.1
       # Am Zielimage gemessen: v1.14.0 traegt 8 CRITICAL und 128 HIGH ueber die
       # drei Images, v1.21.1 traegt 0 und 24.
-      version: "v1.18.6"
+      version: "v1.19.6"
       sourceRef:
         kind: HelmRepository
         name: jetstack