jsonnet: remove incorrect instance:node_filesystem_usage:sum rule

jsonnet/kube-prometheus/rules/node-rules.libsonnet

@@ -8,10 +8,6 @@
             expr: 'sum(rate(node_cpu_seconds_total{mode!="idle",mode!="iowait"}[3m])) BY (instance)',
             record: 'instance:node_cpu:rate:sum',
           },
-          {
-            expr: 'sum((node_filesystem_size_bytes{mountpoint="/"} - node_filesystem_free_bytes{mountpoint="/"})) BY (instance)',
-            record: 'instance:node_filesystem_usage:sum',
-          },
           {
             expr: 'sum(rate(node_network_receive_bytes_total[3m])) BY (instance)',
             record: 'instance:node_network_receive_bytes:rate:sum',