test_validate_remove_file: Clean up /tmp/remove.cfg post testing

[sourabhtk37]

Closes #1248

Signed-off-by: T K Sourab [email protected]

[jenkins-qa-bot]

Can one of the admins verify this patch?

[kylape]

ok to test

[psachin]

@sourabhtk37 With the recent changes in utilities.validate_remove_file I think the tests need to be updated.