hook tests: fix redirection logic error in 96e7225b31

The tests added in 96e7225b31 (hook: add 'run' subcommand,
2021-12-22) were redirecting to "actual" both in the body of the hook
itself and in the testing code below.

The net result was that the "2>>actual" redirection later in the test
wasn't doing anything. Let's have those redirection do what it looks
like they're doing.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>

t/t1800-hook.sh

@@ -95,7 +95,7 @@ test_expect_success 'git hook run -- out-of-repo runs excluded' '
 test_expect_success 'git -c core.hooksPath=<PATH> hook run' '
 	mkdir my-hooks &&
 	write_script my-hooks/test-hook <<-\EOF &&
-	echo Hook ran $1 >>actual
+	echo Hook ran $1
 	EOF
 
 	cat >expect <<-\EOF &&