[kubevirt-operator] Revert incorrect case change in VM alerts

Revert PR #1770 which incorrectly changed status check from lowercase
to uppercase. The actual metrics use lowercase:
- kubevirt_vm_info uses status="running" (not "Running")
- kubevirt_vmi_info uses phase="running" (not "Running")

Verified by querying virt-controller metrics in instories cluster.

Co-Authored-By: Claude <noreply@anthropic.com>
Signed-off-by: Aleksei Sviridkin <f@lex.la>
(cherry picked from commit 36836fd84e)

packages/system/kubevirt-operator/alerts/PrometheusRule.yaml

@@ -27,7 +27,7 @@ spec:
       expr: |
         max_over_time(
           kubevirt_vmi_info{
-            phase!="Running",
+            phase!="running",
             exported_namespace=~".+",
             name=~".+"
           }[10m]