chore(flux): update image registry.k8s.io/kubectl v1.31.1 → v1.31.7 (clustertool) (#33914)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| registry.k8s.io/kubectl | patch | `v1.31.1` -> `v1.31.7` |

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clustertool/embed/generic/kubernetes/system/system-upgrade-controller/app/helm-release.yaml

@@ -38,7 +38,7 @@ spec:
               SYSTEM_UPGRADE_JOB_ACTIVE_DEADLINE_SECONDS: 900
               SYSTEM_UPGRADE_JOB_BACKOFF_LIMIT: 99
               SYSTEM_UPGRADE_JOB_IMAGE_PULL_POLICY: IfNotPresent
-              SYSTEM_UPGRADE_JOB_KUBECTL_IMAGE: registry.k8s.io/kubectl:v1.31.1
+              SYSTEM_UPGRADE_JOB_KUBECTL_IMAGE: registry.k8s.io/kubectl:v1.31.7
               SYSTEM_UPGRADE_JOB_POD_REPLACEMENT_POLICY: Failed
               SYSTEM_UPGRADE_JOB_PRIVILEGED: true
               SYSTEM_UPGRADE_JOB_TTL_SECONDS_AFTER_FINISH: 900