fix(container): update image docker.io/rancher/kubectl to v1.28.4 (#1062)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

bootstrap/templates/addons/system-upgrade-controller/app/helmrelease.yaml.j2

@@ -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: docker.io/rancher/kubectl:v1.28.3
+              SYSTEM_UPGRADE_JOB_KUBECTL_IMAGE: docker.io/rancher/kubectl:v1.28.4
               SYSTEM_UPGRADE_JOB_PRIVILEGED: true
               SYSTEM_UPGRADE_JOB_TTL_SECONDS_AFTER_FINISH: 900
               SYSTEM_UPGRADE_PLAN_POLLING_INTERVAL: 15m