[#2114] Clarify functionality of getHomeFolder for Windows OSes.

Problem
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Difficult to understand code and all ramifications/implications for `getHomeFolder` on Windows.

Changes
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I've tried to clean up the code but did not manage to do a much better job :sob:. Fixed tests for `getHomeFolder`.

Drive-by-fix to report errors when removing home (profile) folders for test users. This wasy we will spot cleaning errors early.

How to test
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reviewers @adiroiban 

Please check that the changed make sense. Github diff is weird, might be better to do a local diff.