[bug] tests depend on siibra-api

[xgui3783]

currently tests require siibra-api to be healthy. While this has some advantages (does not need test data to be hard coded), this also makes the tests significantly more flaky.

e.g.

• if siibra-api is down, the tests will obviously fail
• if siibra-api is polluted with wrong data, tests will fail
• if siibra-api version mismatches, angular tests will fail with cyrptic messages such as "Injector already destroyed" (in the even version mismatches, viewer will display snack message of version mismatch. In a test, the angular app is destroyed before the snackbar message can be properly dismissed)