don't fail listing definitions if the format from the server is invalid

[jrhizor]

#6975 resulted in a duplicate entry resulting in the problem observed in https://airbytehq.slack.com/archives/C01MFR03D5W/p1635865547477900

No invalid input from this file should impact availability of OSS or Cloud installations of Airbyte.

[airbyte-jenny]

Investigating the original report, it looks like #7565 was used to resolve the short-term issue by removing a duplicate source definition from airbyte-config/init/src/main/resources/seed/source_definitions.yaml

This error caused a crash on the onboarding page, at AirbyteRequestService.ts:75 saying there were multiple definitions; this is just a wrapper on making some request to the backend (not entirely obvious which one). We should be able to reproduce by duplicating a definition locally for testing.

[airbyte-jenny]

Modify getLatestSources() and getLatestDefinitions() to catch Throwable. Look for NoInternet test cases and modify that test case file to include formatting problems and json deserialization problems.