Create smoke test to prevent start up crashes when device doesn't have network access

[mcomella]

This is very similar to #18041 The distinction is that this bug is for no network access; that bug is for network access but bad results.

We experienced a start up crash when the device was without network access: #16886 afaict, this was fixed in the nimbus SDK mozilla/nimbus-sdk#67 but there wasn't any generic smoke test put in place to prevent this class of errors (crashes due to having no network access for start up or other UI flows). We should add such a test. This test could be automated or added to the manual QA test plan (then again if it was done manually, it'd still cause our perftests too fail (below) so maybe it's only sufficient if, when we see such crashes, that the perf team is notified directly).

To be explicit, this is not something the performance team intends to work on in the short term but it's important to us because crashes like these cause our performance tests in mozilla-central to fail, which disrupts our engineers' work stream as we investigate such crashes and possibly missing the cause of regressions as we lose performance test data.

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