Fixes #4318 - k0s reset should not delete all when drives fail to unmount

[MichaelDausmann]

Description

Although the issue is closed, #4318 is a serious problem and a critical design flaw IMO. This behaviour recently caused a serious data loss incident at my organisation where a k0s reset command was executed prior to un-mounting critical data as a part of a large and complex release.

If we did not have backup policies in place, this would have been an existential problem for our organisation, as it was, it caused a week of headaches and a large Cloud Egress bill for restoring deleted data.

There is just no way that silent deletion of data is an acceptable behaviour for any software that is intended for enterprise use.

Fixes #4318

Type of change

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [x] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Documentation update

How Has This Been Tested?

• [ ] Manual test
• [ ] Auto test added

I was able to run the unit test suite with no issue but I'm not sure how to really set up a local env and test this properly.

Checklist:

• [ ] My code follows the style guidelines of this project
• [ ] My commit messages are signed-off
• [x] I have performed a self-review of my own code
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] My changes generate no new warnings - 2 new errors for the reset command
• [ ] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [ ] Any dependent changes have been merged and published in downstream modules
• [x] I have checked my code and corrected any misspellings