flaky test TestForClusterServerInfo

[hawkingrei]

Bug Report

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1. Minimal reproduce step (Required)

Binary_plan: tidb_decode_binary_plan('dUwKcQoOTWVtVGFibGVTY2FuXzQpAAEB8EmIw0AwxQM4AUABSiQKIgoSaW5mb3JtYXRpb25fc2NoZW1hEgxDTFVTVEVSX0xPQURaE3RpbWU6MS41MXMsIGxvb3BzOjJw/////wUDNAF4////////////ARgB')\nselect * from information_schema.CLUSTER_LOAD;"]
    cluster_tables_test.go:130: 
        	Error Trace:	/home/jenkins/.tidb/tmp/63a9840cd0739f2c243bb46478607469/sandbox/linux-sandbox/6614/execroot/__main__/bazel-out/k8-fastbuild/bin/infoschema/infoschema_test_/infoschema_test.runfiles/__main__/infoschema/cluster_tables_test.go:130
        	Error:      	"0" is not greater than "0"
        	Test:       	TestForClusterServerInfo

https://do.pingcap.net/jenkins/blue/rest/organizations/jenkins/pipelines/pingcap/pipelines/tidb/pipelines/ghpr_unit_test/runs/9193/nodes/49/steps/54/log/?start=0

2. What did you expect to see? (Required)

3. What did you see instead (Required)

4. What is your TiDB version? (Required)