[e2e] Emit a duration-scoped grafana link for each test

[marun]

Why this should be merged

When an e2e failure occurs in CI, it would be useful to start with a metrics link scoped to the duration of execution of the failing test.

How this works

• Defaults to emitting a metrics link at the end of spec execution
  • A test can disable this behavior by setting e2e.EmitMetricsLink to false
• Composes a metrics link in a global ginkgo AfterEach handler for the shared network UUID and the start/end times of the current spec
  • The end time is extended by the network shutdown delay to account for the network scrape interval

How this was tested

CI

[aaronbuchwald]

Was this meant as a TODO?

[marun]

Not a TODO - this is a reminder to coordinate changes to this value with the value in the script.

FWIW this should be temporary - when I have the cycles I plan to integrate starting of the log and metrics collectors into the e2e framework and that will remove the need for duplicating configuration.

[aaronbuchwald]

Where is handling env == nil necessary?

[marun]

This avoids a broken event handler in the case that there is no global env configured. This is the case for subnet-evm's load test suite for example, where the env is local-only:

https://github.com/ava-labs/subnet-evm/blob/master/tests/load/load_test.go#L60

[marun]

For future, please don't hesitate to wait until someone responds to merge. I would have been happy to add a comment here pre-merge.