Revert nutanix cloud provider version (#5148)

Author: snarkychef

UPSTREAM_PROJECTS.yaml

@@ -251,7 +251,7 @@ projects:
     repos:
       - name: cloud-provider-nutanix
         versions:
-          - tag: v0.6.0
+          - tag: v0.5.5
             go_version: "1.24"
       - name: cluster-api-provider-nutanix
         versions: