Add tests for #12209
Use custom user/group for integration tests for #12209

Not all platforms have a "nobody" user, this commit changes these tests
to use a "test12209" user/group for these tests.
Use new decorators for issue 12209 tests
Add skipIf and destructiveTest

These tests must be run as root, and create and destroy a user and
group, so this adds the proper decorators.

Additionally, this wraps the assertions from these tests in a try/except
block that ensures that the temp directory created for this test is
cleaned up.
Fix import
Remove unnecessary except
Merge pull request #12281 from terminalmage/issue12209-tests

Add tests for #12209