Flexible support of GC collectors in telemetry.

[j-bennet]

Support collectors other than young and old when collecting GC stats in telemetry.

Fixes #1052.

[pquentin]

Thank you, this works perfectly! This is a very polished contribution, it was a pleasure to review. Per our process, not merging, feel free to do it yourself.

If you're looking for a follow up task, since we now store ZGC information in the metrics store, should we go as far as adding the data in the race report and comparison report? This would involve modifying metrics.py and reporter.py, see #1416 for an example.

[j-bennet]

@pquentin

If you're looking for a follow up task, since we now store ZGC information in the metrics store, should we go as far as adding the data in the race report and comparison report? This would involve modifying metrics.py and reporter.py, see #1416 for an example.

Nice, thanks for the tip! I'll follow up on that.