tests: network::fetchlocal: let cleanup function handle sandbox cleanup

Two tests in network::fetchlocal explicitly set a cleanup function to
free and remove the created sandbox repositories. This is not necessary,
though, as the cleanup function executed after each test already takes
care of cleaning up after them. Remove the code to avoid needless code
duplication.

tests/network/fetchlocal.c

@@ -314,12 +314,6 @@ void test_network_fetchlocal__prune_tag(void)
 	git_repository_free(repo);
 }
 
-static void cleanup_sandbox(void *unused)
-{
-	GIT_UNUSED(unused);
-	cl_git_sandbox_cleanup();
-}
-
 void test_network_fetchlocal__partial(void)
 {
 	git_repository *repo = cl_git_sandbox_init("partial-testrepo");
@@ -332,7 +326,6 @@ void test_network_fetchlocal__partial(void)
 	options.callbacks.transfer_progress = transfer_cb;
 	options.callbacks.payload = &callcount;
 
-	cl_set_cleanup(&cleanup_sandbox, NULL);
 	cl_git_pass(git_reference_list(&refnames, repo));
 	cl_assert_equal_i(1, (int)refnames.count);
 
@@ -420,7 +413,6 @@ void test_network_fetchlocal__multi_remotes(void)
 	git_strarray refnames = {0};
 	git_fetch_options options = GIT_FETCH_OPTIONS_INIT;
 
-	cl_set_cleanup(&cleanup_sandbox, NULL);
 	options.callbacks.transfer_progress = transfer_cb;
 	cl_git_pass(git_remote_set_url(repo, "test", cl_git_fixture_url("testrepo.git")));
 	cl_git_pass(git_remote_lookup(&test, repo, "test"));