flaky test TestFlightRecorder

[lybcodes]

Bug Report

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1. Minimal reproduce step (Required)

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

3. What did you see instead (Required)

The test branch is the master branch, and Go 1.25 is used. （https://do.pingcap.net/jenkins/job/pingcap/job/tidb/job/pull_unit_test_next_gen/6689/）

integration_test.go:250: 
        	Error Trace:	pkg/util/traceevent/integration_test.go:250
        	Error:      	Not equal: 
        	            	expected: 0x80
        	            	actual  : 0x20
        	Test:       	TestFlightRecorder

4. What is your TiDB version? (Required)