TestSchedulerDiagnosticAPI failed

[rleungx]

Flaky Test

Which jobs are failing

--- FAIL: TestDiagnosticTestSuite (3.92s)
    --- FAIL: TestDiagnosticTestSuite/TestSchedulerDiagnosticAPI (1.64s)
        api_check.go:29: 
            	Error Trace:	/home/runner/work/pd/pd/pkg/utils/testutil/api_check.go:29
            	            				/home/runner/work/pd/pd/pkg/utils/testutil/api_check.go:142
            	            				/home/runner/work/pd/pd/pkg/utils/testutil/api_check.go:87
            	            				/home/runner/work/pd/pd/server/api/diagnostic_test.go:68
            	            				/opt/hostedtoolcache/go/1.21.3/x64/src/runtime/asm_amd64.s:1650
            	Error:      	Not equal: 
            	            	expected: 200
            	            	actual  : 500
            	Test:       	TestDiagnosticTestSuite/TestSchedulerDiagnosticAPI
            	Messages:   	resp: "[PD:diagnostic:ErrNoDiagnosticResult]balance-region-scheduler has no diagnostic result"
        diagnostic_test.go:66: 
            	Error Trace:	/home/runner/work/pd/pd/server/api/diagnostic_test.go:66
            	            				/home/runner/work/pd/pd/server/api/diagnostic_test.go:110
            	Error:      	Condition never satisfied
            	Test:       	TestDiagnosticTestSuite/TestSchedulerDiagnosticAPI

CI link

https://github.com/tikv/pd/actions/runs/6794492910/job/18470995029?pr=7335

Reason for failure (if possible)

Anything else