t6022: Remove unnecessary untracked files to make test cleaner

Since this test later does a git add -A, we should clean out unnecessary
untracked files as part of our cleanup.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t6022-merge-rename.sh

@@ -252,6 +252,7 @@ test_expect_success 'setup for rename + d/f conflicts' '
 	git reset --hard &&
 	git checkout --orphan dir-in-way &&
 	git rm -rf . &&
+	git clean -fdqx &&
 
 	mkdir sub &&
 	mkdir dir &&