e2e: Acknowledge xhr failures

Our e2e test suite currently ignores failed xhr calls, I think this could lead to missed bugs or regressions when calling our own APIs from a web page, especially with 5xx status codes.

This MR intercepts all http calls done by cypress and asserts their returning status code is < 500 and fixes a small bug in the admin_deposit_list view due to the stripped down deposit config in the test environment (see settings.tests).