t1410: use test-tool to create empty reflog

One of the tests in t1410 is marked to be specific to the files
reference backend, which is because we create a reflog manually by
creating the respective file. Refactor the test to instead use our
`test-tool ref-store` helper to create the reflog so that it works with
other reference backends, as well.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

t/t1410-reflog.sh

@@ -469,11 +469,11 @@ test_expect_success 'expire one of multiple worktrees' '
 	)
 '
 
-test_expect_success REFFILES 'empty reflog' '
+test_expect_success 'empty reflog' '
 	test_when_finished "rm -rf empty" &&
 	git init empty &&
 	test_commit -C empty A &&
-	>empty/.git/logs/refs/heads/foo &&
+	test-tool ref-store main create-reflog refs/heads/foo &&
 	git -C empty reflog expire --all 2>err &&
 	test_must_be_empty err
 '