Fix recursive file listing in volumes

[MeinAccount]

What changes are proposed in this pull request?

Fix recursive file listing on volumes. Fixes #1260 . The new code is analogous to _DbfsPath, were the recursion also happens on file.path.

How is this tested?

Manually tested on a volume with sub-sub-directories using

print(list(client.dbfs.list("/Volumes/...", recursive=True)))

[github-actions]

If integration tests don't run automatically, an authorized user can run them manually by following the instructions below:

Trigger:
go/deco-tests-run/sdk-py

Inputs:

• PR number: 1261
• Commit SHA: cfe463971ce468ca68f057537dc9771d4abffb48

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