t9834: remove use of `test_might_fail p4`

The test_must_fail() family of functions (including test_might_fail())
should only be used on git commands. Replace test_might_fail() with
a compound command wrapping the old p4 invocation that always returns 0.

Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t9834-git-p4-file-dir-bug.sh

@@ -10,7 +10,7 @@ repository.'
 
 test_expect_success 'start p4d' '
 	start_p4d &&
-	test_might_fail p4 configure set submit.collision.check=0
+	{ p4 configure set submit.collision.check=0 || :; }
 '
 
 test_expect_success 'init depot' '