t5580: don't create unused file

The file "out" was introduced by 13b57da833 (mingw: verify that paths
are not mistaken for remote nicknames, 2017-05-29), but has not actually
been used then and since.  Get rid of it.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t5580-clone-push-unc.sh

@@ -58,7 +58,7 @@ test_expect_success push '
 
 test_expect_success MINGW 'remote nick cannot contain backslashes' '
 	BACKSLASHED="$(winpwd | tr / \\\\)" &&
-	git ls-remote "$BACKSLASHED" >out 2>err &&
+	git ls-remote "$BACKSLASHED" 2>err &&
 	test_i18ngrep ! "unable to access" err
 '