While our tests in config::include create a plethora of configuration
files, most of them do not get removed at the end of each test. This can
cause weird interactions with tests that are being run at a later stage
if these later tests try to create files or directories with the same
name as any of the created configuration files.

Fix the issue by unlinking all created files at the end of these tests.

(cherry picked from commit bf662f7c)