dbaas: pg-cluster threshold 80%→10% in CNPG inheritedMetadata

Same misconfig as the bulk fecfa211 sweep, but the pg-cluster YAML
is buried inside a null_resource local-exec heredoc so the regex
didn't catch it. CNPG operator inherits these annotations onto each
member PVC (pg-cluster-1, pg-cluster-2), and reapplies them on every
reconcile — patching the live PVCs alone bounces back within seconds.

Live state already patched via kubectl patch cluster, this just keeps
TF in sync.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

stacks/dbaas/modules/dbaas/main.tf

@@ -1075,7 +1075,9 @@ resource "null_resource" "pg_cluster" {
         enableSuperuserAccess: true
         inheritedMetadata:
           annotations:
-            resize.topolvm.io/threshold: "80%"
+            # threshold = free-space % below which autoresizer expands.
+            # 10% means "expand when 90% used" (the conventional knob).
+            resize.topolvm.io/threshold: "10%"
             resize.topolvm.io/increase: "20%"
             resize.topolvm.io/storage_limit: "100Gi"
         storage: