Filter events the env exposes in test snapshots to contracts to contract events

[leighmcculloch]

What

Filter events the env exposes in test snapshots to contracts to contract events.

Why

The main thing we need to test in test snapshots is that non-diagnostic events are consistent and captured.

Diagnostic events are noise here.

Notes

There's no good time to make this change.

Ideally the change is made at a major version because it's breaking.

But at a major version is the ideal time to avoid the change so that people see only meaningful diffs on their test snapshots.

[leighmcculloch]

@dmkozh Maybe we should also retain system events. I don't actually remember what system events exist though...

[dmkozh]

Maybe we should also retain system events. I don't actually remember what system events exist though...

Yeah, let's retain system events. They're underutilized, but we do currently emit a system event for the contract updates.

[leighmcculloch]

@dmkozh I've updated it to retain system events. Ready for review.

[graydon]

I don't feel strongly about this as a feature/change either way; but practically it looks like a correct implementation so approving.