add test cases for getShuttlesBySystemIzd

test/repositories/ApiBasedRepositoryTests.test.ts

@@ -510,3 +510,12 @@ describe("getShuttleById", () => {
   });
 });
 
+describe("getShuttlesBySystemId", () => {
+  test("getShuttlesBySystemId returns old data if not expired", async () => {
+
+  });
+
+  test("getShuttlesBySystemId returns fresh data if expired", async () => {
+
+  });
+})