flaky test: prefixNext failed with wait table tiflash replica timed out

[yongman]

Bug Report

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1. Minimal reproduce step (Required)

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

3. What did you see instead (Required)

fullstack-test2/clustered_index/prefixNext.test: Running
  File: fullstack-test2/clustered_index/prefixNext.test
  Error line: 21
  Error: wait_table test t1
  Error: test timed out after 120s
fullstack-test2/clustered_index/prefixNext.test: Failed

columnar-replica-timeout.log

4. What is your TiFlash version? (Required)