Refactor: Replace network-dependent test fixture with local testdata in convert_metrics

[Syedowais312]

Hey, I've been looking at the integration test in cmd/convert_metrics/convert_metrics_test.go and noticed it currently downloads a zip from GitHub at test runtime to get the metrics fixtures. This makes the test slow and flaky (network dependency, GitHub rate limits, zip structure changes could silently break it).

I refactored it to use a local testdata/metrics/ fixture instead a minimal but representative set covering:

• A metric with versioned SQL (example_metric/11/metric_master.sql)
• A helper that gets wired as init_sql (00_helpers/helper_fn/11/metric.sql)
• A preset (basic) that references the metric

The test runs in ~0.005s now vs waiting on a network round trip, and the assertions verify the core converter behavior (metrics, init_sql, presets) still works correctly.

Should I go ahead and open a PR for this? Happy to expand the testdata if the current fixture feels too minimal, or keep it as-is if the goal is just to verify the converter wiring rather than exhaustive coverage.

Was the pgwatch2 URL intentional i.e. is the converter meant to handle real pgwatch2 metrics as input?

Let me know your thoughts.

CC: @pashagolub @0xgouda

[pashagolub]

hey! thanks for your suggestion! I will remove the utility completely. Enough time passed since v2, so there is no need in keeping it.

[pashagolub]

addressed by #1313

[Syedowais312]

Closing as completed!

Thank you.