Unstable test `TestStalenessAndHistoryRead`

[tangenta]

Enhancement

--- FAIL: TestStalenessAndHistoryRead (1.27s)
    testkit.go:291: cleaned up ddl and tables
    stale_read_test.go:413: 
        	Error Trace:	/home/jenkins/agent/workspace/pingkai/tidb/pr-verify/tidb/tests/realtikvtest/txntest/stale_read_test.go:413
        	Error:      	Not equal: 
        	            	expected: 71
        	            	actual  : 72
        	Test:       	TestStalenessAndHistoryRead
FAIL