Increase memory limits for metal-ipi openshift-tests (#48951)

This was increased recently for  golang/go#64332 but
metal-ipi bm jobs persist in being OOM'd. Bump it further.

Author: derekhiggins

ci-operator/step-registry/baremetalds/e2e/test/baremetalds-e2e-test-ref.yaml

@@ -9,7 +9,7 @@ ref:
       cpu: "3"
       memory: 600Mi
     limits:
-      memory: 10Gi
+      memory: 12Gi
   env:
   - name: ARCHITECTURE
     default: "amd64"