HDFS-17927. Make TestDiskError.testShutdown use deterministic volume failure injection

[smengcl]

Description of PR

TestDiskError.testShutdown() currently drives DataNode shutdown by repeatedly creating files until dn.isDatanodeUp() becomes false. If shutdown does not happen promptly, the test can loop for a long time and generate excessive logs.

This change replaces the file-create loop with deterministic failure injection for both DataNode data dirs, then explicitly runs dn.checkDiskError() and waits boundedly for the DataNode to exit.

How was this patch tested?

• The test TestDiskError.testShutdown itself.

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[Copilot]

Pull request overview

This PR makes TestDiskError.testShutdown() deterministic by replacing repeated file creation with direct DataNode volume failure injection and a bounded wait for shutdown.

Changes:

• Uses DataNodeTestUtils.injectDataDirFailure() on both DataNode storage dirs.
• Calls dn.checkDiskError() directly and waits up to 30 seconds for the DataNode to report down.
• Cleans up injected failures in a finally block and updates imports accordingly.

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[boky01]

Are we sure the 2 additional DNs are not required neither in this test case nor to keep the following test cases stable (in the setup phase we are creating a single DN cluster)?

[boky01]

Is it possible to reach this line?
I mean if dn.isDatanodeUp() is true, then GenericTestUtils.waitFor(() will throw an exception, so if GenericTestUtils.waitFor() did not throw exception that means the DN is down.

[boky01]

Hi @smengcl,
Thanks for the patch, it's a better version then the previous one. I left a few comments, please check them.