flaky test TestMemTracker4InsertAndReplaceExec

[hawkingrei]

Bug Report

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1. Minimal reproduce step (Required)

    oom_test.go:119: 
        	Error Trace:	/home/jenkins/.tidb/tmp/63a9840cd0739f2c243bb46478607469/sandbox/linux-sandbox/7242/execroot/__main__/bazel-out/k8-fastbuild/bin/executor/oomtest/oomtest_test_/oomtest_test.runfiles/__main__/executor/oomtest/oom_test.go:119
        	Error:      	Not equal: 
        	            	expected: ""
        	            	actual  : "region 2 acquire 6 locks takes 72.987605ms, waitCnt 0"
        	            	
        	            	Diff:
        	            	--- Expected
        	            	+++ Actual
        	            	@@ -1 +1 @@
        	            	-
        	            	+region 2 acquire 6 locks takes 72.987605ms, waitCnt 0
        	Test:       	TestMemTracker4InsertAndReplaceExec

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

3. What did you see instead (Required)

4. What is your TiDB version? (Required)