Add a new operation in stressmasterbench to generate complex file tree

[shuaiwuyue]

What changes are proposed in this pull request?

Add a new operation, CreateKAryTree, in StressMasterBench for generating the complex file tree. This operation will create a number of files and folders under the target directory, and they will be organized in the form of a complete K-ary tree.

Why are the changes needed?

CreateFile or CreateDir operation can only create a simple and flat file tree. This file tree limits some tests such as metadata-sync and can't represent the real-world workload. So CreateKAryTree operation is designed for generating the complex file tree.

Does this PR introduce any user facing changes?

None

[alluxio-bot]

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[alluxio-bot]

Automated checks report:

• Commits associated with Github account: PASS
• PR title follows the conventions: PASS

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[github-actions[bot]]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in two weeks if no further activity occurs. Thank you for your contributions.

[github-actions[bot]]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in two weeks if no further activity occurs. Thank you for your contributions.