unstable unit test indexmergereadtest

[lyzx2001]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

Run unit tests.

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

All unit tests should pass.

3. What did you see instead (Required)

622:==================== Test output for //executor/test/indexmergereadtest:indexmergereadtest_test (shard 29 of 30):
623:=== RUN   TestOrderByWithLimit
2091:-- Test timed out at 2023-07-11 15:08:44 CST --
2092:================================================================================
2093:==================== Test output for //executor/test/indexmergereadtest:indexmergereadtest_test (shard 29 of 30):
2094:=== RUN   TestOrderByWithLimit
3216:-- Test timed out at 2023-07-11 15:11:17 CST --
3217:================================================================================
3218:==================== Test output for //executor/test/indexmergereadtest:indexmergereadtest_test (shard 29 of 30):
3219:=== RUN   TestOrderByWithLimit
4312:-- Test timed out at 2023-07-11 15:13:49 CST --
4313:================================================================================

https://do.pingcap.net/jenkins/blue/organizations/jenkins/pingcap%2Ftidb%2Fghpr_unit_test/detail/ghpr_unit_test/28160/pipeline/
https://do.pingcap.net/jenkins/job/pingcap/job/tidb/job/ghpr_unit_test/28160/artifact/bazel-go-test-index.log

4. What is your TiDB version? (Required)

Release Version: v7.2.0

[hawkingrei]

It has been fixed by #45249.