Fix repair tool test failure

https://dev.azure.com/apache-hudi-ci-org/785b6ef4-2f42-4a89-8f0e-5f0d7039a0cc/_apis/build/builds/8118/logs/18
{code:java}
2022-04-19T00:28:13.1889666Z [ERROR] Tests run: 9, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 5.786 s <<< FAILURE! - in org.apache.hudi.utilities.TestHoodieRepairTool
2022-04-19T00:28:13.1890526Z [ERROR] org.apache.hudi.utilities.TestHoodieRepairTool.testUndoWithExistingBackupPath Time elapsed: 0.362 s <<< ERROR!
2022-04-19T00:28:13.1891118Z org.apache.spark.SparkException:
2022-04-19T00:28:13.1891920Z Job aborted due to stage failure: Task 0 in stage 14.0 failed 1 times, most recent failure: Lost task 0.0 in stage 14.0 (TID 49, localhost, executor driver): org.apache.hudi.exception.HoodieIOException: Failed to list /tmp/junit3223059486957425857/backup
2022-04-19T00:28:13.1892896Z at org.apache.hudi.common.fs.FSUtils.lambda$getFileStatusAtLevel$94bae19f$1(FSUtils.java:791) {code}

## JIRA info

- Link: https://issues.apache.org/jira/browse/HUDI-3909
- Type: Test
- Epic: https://issues.apache.org/jira/browse/HUDI-3303

Start with org.apache.hudi.utilities.TestHoodieRepairTool.testUndoWithExistingBackupPath and the linked build log, which reports a failure listing the backup path. Investigate why the test errors, then rerun it; done means the test passes.

Written by the indexing model from the issue text.