use global fetch mock for old data test

test/repositories/ApiBasedRepositoryTests.test.ts

@@ -224,6 +224,8 @@ describe("getEtaForShuttleAndStopId", () => {
   });
 
   test("getEtasForShuttleAndStopId returns old data if not expired", async () => {
+    updateGlobalFetchMockJson(genericEtaDataByStopId);
+
     const expectedEta: IEta = {
       secondsRemaining: 587,
       shuttleId: "5577",