Unstable test TestPlanCacheWithStaleReadByBinaryProto

[gengliqi]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

run TestPlanCacheWithStaleReadByBinaryProto test several times.

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

Test succeed.

3. What did you see instead (Required)

--- FAIL: TestPlanCacheWithStaleReadByBinaryProto (0.17s)
    result.go:50: 
                Error Trace:    result.go:50
                                                        stale_txn_test.go:1315
                Error:          Not equal: 
                                expected: "[1 10]\n"
                                actual  : ""
                            
                                Diff:
                                --- Expected
                                +++ Actual
                                @@ -1,2 +1 @@
                                -[1 10]
                                 
                Test:           TestPlanCacheWithStaleReadByBinaryProto
                Messages:       &{0x140055dbae0 0x1400468c000 0x140046da1a0}
FAIL

4. What is your TiDB version? (Required)

master

[gengliqi]

/assign @Yisaer