[BUG] mvcc_trx_log_test occasional failed

[nautaa]

Describe the bug
A clear and concise description of what the bug is.
ref: https://github.com/oceanbase/miniob/actions/runs/10556062499/job/29240856790

[ RUN      ] MvccTrxLog.wal_rollback_abnormal
27: /home/runner/work/miniob/miniob/unittest/observer/mvcc_trx_log_test.cpp:711: Failure
27: Expected equality of these values:
27:   visible_count
27:     Which is: 499
27:   insert_num / 2
27:     Which is: 500
27: [  FAILED  ] MvccTrxLog.wal_rollback_abnormal (31718 ms)

** Environment**
Environment Details sometimes important

• OS Version:
• CPU Arch(x86/arm):
• Compiler:
• Others:

Fast Reproduce Steps(Required)
Steps to reproduce the behavior:

Expected behavior
A clear and concise description of what you expected to happen.

Actual Behavior
What is the result? picture is allowed

Additional context
Add any other context about the problem here.