Remove moot setup code

[elharo]

start on #1316

test fails by IOException if the directory can't be deleted. The asserts never fail if they're reached.

[Copilot]

Pull Request Overview

This PR removes unnecessary setup code from the ScmTestCase class that performed redundant assertions after directory deletions. The change eliminates assert statements that verified directories were deleted and removes an unused import and variable assignment.

• Removes assertFalse statements that checked directory deletion
• Removes unused assertFalse import
• Removes redundant scmManager = null assignment

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